Simple Interest
1. How much time will it take for an amount of Rs. 450 to yield Rs. 81 as interest at 4.5% per annum of simple interest?
A. 3.5 years
B. 4 years
C. 4.5 years
D. 5 years
Answer: Option B
Explanation:
Time = ([latex]\frac {100 \times 81}{450 \times 4.5}[/latex]) years = 4 years.
2. An automobile financier claims to be lending money at simple interest, but he includes the interest every six months for calculating the principal. If he is charging interest of 10%, the effective rate of interest becomes:
A. 10%
B. 10.25%
C. 10.5%
D. None of these
Answer: Option B
Explanation:
Let the sum be Rs. 100. Then,
S.I. for first 6 months = Rs. ([latex]\frac {100 \times 10 \times 1}{100 \times 2}[/latex]) = Rs. 5
S.I. for last 6 months = Rs. ([latex]\frac {105 \times 10 \times 1}{100 \times 2}[/latex]) = Rs. 5.25
So, amount at the end of 1 year = Rs. (100 + 5 + 5.25) = Rs. 110.25
Effective rate = (110.25 - 100) = 10.25%
Height and Distance
1. Two houses are in front of each other. Both have chimneys on their top. The line joining the chimneys makes an angle of 45° with the ground. How far are the houses from each other if one house is 25m and other is 10m in height?
A. 18 m
B. 12 m
C. 7.5 m
D. 15 m
Answer: Option D
Explanation:
2. Tree top’s angle of elevation is 30° from a point on the ground, 300m away from the tree. When the tree grew up its angle of elevation became 60° from the same point. How much did the tree grow?
A. 100[latex]\frac {1}{2}[/latex] m
B. 200[latex]\sqrt {3}[/latex] m
C. 300(1/[latex]\sqrt {3}[/latex])
D. 200/[latex]\sqrt {3}[/latex] m
Answer: Option B
Explanation
3. A tree breaks and falls to the ground such that its upper part is still partially attached to its stem. At what height did it break, if the original height of the tree was 24 cm and it makes an angle of 30° with the ground?
A. 12 cm
B. 8 cm
C. 9.5 cm
D. 7.5 cm
Answer: Option B
Explanation:
Volume and Surface Area
1. 66 cubic centimeters of silver is drawn into a wire 1 mm in diameter. The length of the wire in meters will be:
A. 84
B. 90
C. 168
D. 336
Answer: Option A
Explanation:
Let the length of the wire be h.
Radius =[latex]\frac {1}{2}[/latex] mm = [latex]\frac {1}{20}[/latex] cm. Then,
[latex]\frac {22}{7}[/latex] x [latex]\frac {1}{20}[/latex] x [latex]\frac {1}{20}[/latex] x h = 66.
h = ([latex]\frac {66 \times 20 \times 20 \times 7}{22}[/latex]) = 8400 cm = 84 m.
2. A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:
A. 3.6 kg
B. 3.696 kg
C. 36 kg
D. 36.9 kg
Answer: Option B
Explanation:
External radius = 4 cm,
Internal radius = 3 cm.
Volume of iron
= ([latex]\frac {22 \times [(4)^{2} - (3)^{2}] \times 21}{7}[/latex]) cm3
= ([latex]\frac {22}{7}[/latex] x 7 x 1 x 21) cm3
= 462 cm3.
Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.
3. A cistern 6m long and 4 m wide contains water up to a depth of 1 m 25 cm. The total area of the wet surface is:
A. 49 m[latex]^{2}[/latex]
B. 50 m[latex]^{2}[/latex]
C. 53.5 m[latex]^{2}[/latex]
D. 55 m[latex]^{2}[/latex]
Answer: Option A
Explanation:
Area of the wet surface = [2(lb + bh + lh) - lb]
= 2(bh + lh) + lb
= [2 (4 x 1.25 + 6 x 1.25) + 6 x 4] m[latex]^{2}[/latex]
= 49 m[latex]^{2}[/latex].
Logarithm
1. Which of the following statements is not correct?
A. log[latex]_{10}[/latex] 10 = 1
B. log (2 + 3) = log (2 x 3)
C. log[latex]_{10}[/latex] 1 = 0
D. log (1 + 2 + 3) = log 1 + log 2 + log 3
Answer: Option B
Explanation:
(a) Since log[latex]_{a}[/latex] a = 1, so log[latex]_{10}[/latex] 10 = 1.
(b) log (2 + 3) = log 5 and log (2 x 3) = log 6 = log 2 + log 3
log (2 + 3) ≠ log (2 x 3)
(c) Since log[latex]_{a}[/latex]a 1 = 0, so log[latex]_{10}[/latex] 1 = 0.
(d) log (1 + 2 + 3) = log 6 = log (1 x 2 x 3) = log 1 + log 2 + log 3.
So, (b) is incorrect.
2. If log 27 = 1.431, then the value of log 9 is:
A. 0.934
B. 0.945
C. 0.954
D. 0.958
Answer: Option C
Explanation:
log 27 = 1.431
log (3[latex]^{3}[/latex] ) = 1.431
3 log 3 = 1.431
log 3 = 0.477
log 9 = log(3[latex]^{2}[/latex]) = 2 log 3 = (2 x 0.477) = 0.954.
3. If log[latex]_{10}[/latex] 2 = 0.3010, then log[latex]_{2}[/latex] 10 is equal to:
A. [latex]\frac {699}{301}[/latex]
B. [latex]\frac {1000}{301}[/latex]
C. 0.3010
D. 0.6990
Answer: Option B
Explanation:
log[latex]_{2}[/latex] 10 = [latex]\frac {1}{log_{10} 2}[/latex] = [latex]\frac {1}{0.3010}[/latex] = [latex]\frac {10000}{3010}[/latex] = [latex]\frac {1000}{301}[/latex].
Races and Games
1. In a 100 m race, A can give B 10 m and C 28 m. In the same race B can give C:
A. 18 m
B. 20 m
C. 27 m
D. 9 m
Answer: Option B
Explanation:
A : B = 100 : 90.
A : C = 100 : 72.
B : C =[latex]\frac {B}{A}[/latex] x [latex]\frac {A}{C}[/latex] = [latex]\frac {90}{100}[/latex] x [latex]\frac {100}{72}[/latex] = [latex]\frac {90}{72}[/latex].
When B runs 90 m, C runs 72 m.
When B runs 100 m, C runs ([latex]\frac {72}{90}[/latex] x 100)m = 80 m.
B can give C 20 m.
2. A and B take part in 100 m race. A runs at 5 kmph. A gives B a start of 8 m and still beats him by 8 seconds. The speed of B is:
A. 5.15 kmph
B. 4.14 kmph
C. 4.25 kmph
D. 4.4 kmph
Answer: Option B
Explanation:
A's speed = 5 x [latex]\frac {5}{18}[/latex] m/sec = [latex]\frac {25}{18}[/latex]m/sec.
18
Time taken by A to cover 100 m = (100 x [latex]\frac {18}{25}[/latex])sec = 72 sec.
Time taken by B to cover 92 m = (72 + 8) = 80 sec.
B's speed = ([latex]\frac {92}{80}[/latex] x [latex]\frac {18}{5}[/latex])kmph = 4.14 kmph.
3. In a 200 meters race A beats B by 35 m or 7 seconds. A's time over the course is:
A. 40 sec
B. 47 sec
C. 33 sec
D. None of these
Answer: Option C
Explanation:
B runs 35 m in 7 sec.
B covers 200 m in ([latex]\frac {7}{35}[/latex] x 200) = 40 sec.
B's time over the course = 40 sec.
A's time over the course (40 - 7) sec = 33 sec.
Simplification
1. What should come in place of question mark (?) in the following question?
8100 ÷ 15 ÷ 5 =?
A. 215
B. 109.68
C. 185.56
D. 108
E. None of these
Answer: Option D
Solution:
8100 ÷ 15 ÷ 5 =?
When this type of situation arises where the same type of signs are present then we solve the given expression from left to right.
⇒ (8100/15) ÷ 5 = ?
⇒ 540 ÷ 5 =?
⇒ ? = 108
2. Find the value of (25 × (10 + 5) – 15) ÷ 62
A. 20
B. 10
C. 60
D. 0
E. None of these
Answer: Option B
Explanation:
Follow BODMAS rule to solve this question, as per the order is given below,
Step-1- Parts of an equation enclosed in 'Brackets' must be solved first, and in the bracket, the BODMAS rule must be followed,
Step-2- Any mathematical 'Of' or 'Exponent' must be solved next,
Step-3-Next, the parts of the equation that contains 'Division' and 'Multiplication' are calculated,
Step-4-Last but not least, the parts of the equation that contains 'Addition' and 'Subtraction' should be calculated.
The given expression is,
(25 × (10 + 5) – 15) ÷ 62
= (25 × 15 – 15) ÷ 62
= (375 - 15) ÷ 62
= 360 ÷ 62
= 360 ÷ 36
= 10
3. The price of 2 sarees and 4 shirts is Rs. 1600. With the same money, one can buy 1 saree and 6 shirts. If one wants to buy 12 shirts, how much shall he have to pay?
A. Rs. 1200
B. Rs. 2400
C. Rs. 4800
D. Cannot be determined
E. None of these
Answer: Option B
Explanation:
Let the price of a saree and a shirt be Rs. x and Rs. y respectively.
Then, 2x + 4y = 1600 .... (i)
and x + 6y = 1600 .... (ii)
Divide equation (i) by 2, we get the below equation.
=> x + 2y = 800. --- (iii)
Now subtract (iii) from (ii)
x + 6y = 1600 (-)
x + 2y = 800
----------------
4y = 800
----------------
Therefore, y = 200.
Now apply the value of y in (iii)
=> x + 2 x 200 = 800
=> x + 400 = 800
Therefore x = 400
Solving (i) and (ii) we get x = 400, y = 200.
Cost of 12 shirts = Rs. (12 x 200) = Rs. 2400.
Time and Distance
1. A car traveling with [latex]\frac {5}{7}[/latex] of its actual speed covers 42 km in 1 hr 40 min 48 sec. Find the actual speed of the car.
A. 17[latex]\frac {6}{7}[/latex] km/hr
B. 25 km/hr
C. 30 km/hr
D. 35 km/hr
Answer: Option D
Explanation:
Time taken = 1 hr 40 min 48 sec = 1 hr 40 [latex]\frac {4}{5}[/latex]min = 1 [latex]\frac {51}{75}[/latex]hrs =[latex]\frac {126}{75}[/latex]hrs.
Let the actual speed be x km/hr.
Then, [latex]\frac {5}{7}[/latex] x x [latex]\frac {126}{75}[/latex] = 42
x = [latex]\frac {42 \times 7 \times 75 }{5 \times 126}[/latex] = 35 km/hr.
2. Robert is traveling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph, he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?
A. 8 kmph
B. 11 kmph
C. 12 kmph
D. 14 kmph
Answer: Option C
Explanation:
Let the distance traveled by x km.
Then,[latex]\frac {x}{10}[/latex] - [latex]\frac {x}{15}[/latex] = 2
3x - 2x = 60
x = 60 km.
Time taken to travel 60 km at 10 km/hr = [latex]\frac {60}{10}[/latex]hrs = 6 hrs.
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
Required speed =[latex]\frac {60}{5}[/latex] kmph. = 12 kmph.
3. A man covered a certain distance at some speed. Had he moved 3 kmph faster, he would have taken 40 minutes less. If he had moved 2 kmph slower, he would have taken 40 minutes more. The distance (in km) is:
A. 35
B. 36[latex]\frac {1}{3}[/latex]
C. 37[latex]\frac {1}{2}[/latex]
D. 40
Answer: Option D
Explanation:
Let distance = x km and usual rate = y kmph.
Then, [latex]\frac {x}{y}[/latex] - [latex]\frac {x}{y+3}[/latex] = [latex]\frac {40}{60}[/latex] => 2y(y + 3) = 9x ....(i)
And,[latex]\frac {x}{y-2}[/latex] - [latex]\frac {x}{y}[/latex] = [latex]\frac {40}{60}[/latex] => y(y - 2) = 3x ....(ii)
On dividing (i) by (ii), we get: x = 40.
Chain Rule
1. 5 mat-weavers can weave 5 mats in 5 days. At the same time, how many mats would be woven by 10 mat- weavers in 10 days?
A. 10 mats
B. 15 mats
C. 20 mats
D. 30 mats
Answer: Option c
Explanation:
Total 5 mats can be weaved in 5 days by 5 weavers.
\[ 5 : x ::
\begin{cases}
30 : 40 - - - (Men)\\
5 : 3 - - - (Days)
\end{cases}
\]
5 × 5 × x = 10 × 10 × 5
x = [latex]\frac {10 \times 10 \times 5}{5 \times 5}[/latex] = 20
20 mats can be weaved in 10 days by 10 mat weavers.
2. If 30 men can do a piece of work in 20 hours, then in how many hours will 12 men do it?
A. 18 hours
B. 30 hours
C. 40 hours
D. 50 hours
Answer: Option D
Explantion:
As number of workers increase, the time required decreases. Hence, this is a problem related to indirect proportion.
Workers (↑),Time (↓)
Let the number of hours be x.
12 : 30 :: 20 : x
[latex]\frac {20}{30}[/latex] = [latex]\frac {20}{X}[/latex]
x = [latex]\frac {20 \times 30}{12}[/latex] = 50
12 men require 50 hours to complete the same work.
3. 18 men bind 900 books in 10 days. Find how many binders will be required to bind 600 books in 12 days?
Answer: Option A
Explanation:
We have to find the number of binders. Let the number of binders be x.
Direct Proportion:Less Books (↓),Less binders(↓)
Indirect Proportion:More days (↑),Less binders (↓)
\[ 18 : x ::
\begin{cases}
900 : 600 - - - (Books) \\
12 : 10 - - - (Days)
\end{cases}
\]
x × 900 × 12 = 18 × 600 × 10
x = [latex]\frac {18 \times 600 \times 10}{900 \times 12}[/latex] = 10
Permutation and Combination
1. How many words can be formed by using letters of the word ‘DELHI’?
Answer: Option D
Explanation:
The word ‘DELHI’ contains 5 letters
Therefore, required number of words = [latex]^5P_{5}[/latex] = 5! = (5 × 4 × 3 × 2 × 1) = 120
120 words can be formed by using letters of the word ‘DELHI’
2. Find the number of ways the letters of the word ‘RUBBER can be arranged?
A. 450
B. 362
C. 250
D. 180
Answer: Option D
Explanation:
The word ‘RUBBER’ contains 6 letters: 2R, 2B, 1 U, 1 E
Therefore,
The required Number of ways: [latex]\frac {N!}{(2R!) \times (2B!) \times (1U!) \times (1E!)}[/latex]
= [latex]\frac {6!}{(2 × 1) \times (2 × 1) \times (1) \times (1)}[/latex]
= [latex]\frac {6 \times 5 \times 4 \times 3 \times 2 \times 1}{4}[/latex]
= 6 × 5 × 3 × 2
= 180
3. Find the value of [latex]^{20}c_{17}[/latex]
A. 1260
B. 1140
C. 2580
D. 3200
Answer: Option B
Explanation:
[latex]^nc_{r}[/latex] =[latex]\frac {^np_{r!}}{r!}[/latex]
[latex]^nc_{r}[/latex] = [latex]\frac {n!}{(r!) (n – r)!}[/latex]
[latex]^{20}c_{17}[/latex] =[latex]\frac {20!}{(17!) (20 – 17)!}[/latex]
[latex]^{20}c_{17}[/latex] =[latex]\frac {20 \times 19 \times 18 \times 17!}{(17!) (3)!}[/latex]
[latex]^{20}c_{17}[/latex] =[latex]\frac {20 \times 19 \times 18}{3 \times 2 \times 1}[/latex]
[latex]^{20}c_{17}[/latex] = 1140.
Surds and Indices
1. If a and b are whole numbers such that a[latex]^{b}[/latex] = 121, then find the value of (a – 1)[latex]^{b + 1}[/latex]
A. 0
B. 10
C. 10[latex]^{2}[/latex]
D. 10[latex]^{3}[/latex]
Answer: Option D
Explanation:
121 = 11[latex]^{2}[/latex] , hence value of a = 11 and b = 2 can be considered.
Therefore, the value of (a – 1)[latex]^{b + 1}[/latex] = (11 – 1)[latex]^{2 + 1}[/latex] = 10[latex]^{3}[/latex]
2. If 4 [latex]^{(x - y)}[/latex] = 64 and 4 [latex]^{(x + y)}[/latex] = 1024, then find the value of x.
Answer: Option D
Explanation:
4 [latex]^{(x - y)}[/latex] = 64
4 [latex]^{(x - y)}[/latex] = 64 = 43
Equation 1. x – y = 3
4 [latex]^{(x + y)}[/latex] = 1024 = 4[latex]^{5}[/latex]
Equation 2. x + y = 5
Solving equation (1) and (2), we get
x = 4 and y = 1
Crosscheck the answers by substituting the values of x and y in the given expression.
4 [latex]^{(4 – 1)}[/latex]= 4[latex]^{3}[/latex] = 64 and 4 [latex]^{(4 + 1)}[/latex] = 4[latex]^{5}[/latex] = 1024
Hence, the answers x = 4 and y = 1 are correct.
3. (1331)[latex]^{- (2/3)}[/latex]
A. –[latex]\frac {1}{11}[/latex]
B. – [latex]\frac {11}{121}[/latex]
C. [latex]\frac {1}{122}[/latex]
D. [latex]\frac {121}{11}[/latex]
Answer: Option C
Explanation:
Cube root of 1331 is 11. Therefore,
(11)[latex]^{3 \times -(2/3)}[/latex]
Remember the law of indices (xm)n = xmn
(11)[latex]^{3 \times -(2/3)}[/latex] = 11[latex]^{-2}[/latex]
x[latex]^{-1}[/latex] = [latex]\frac {1}{x}[/latex]
Hence, 11[latex]^{-2}[/latex] = [latex]\frac {1}{112}[/latex] = [latex]\frac {1}{112}[/latex]
Pipes and Cistern
1. Two pipes A & B can fill the tank in 12 hours and 36 hours respectively. If both the pipes are opened simultaneously, how much time will be required to fill the tank?
A. 6 hours
B. 9 hours
C. 12 hours
D. 15 hours
Answer: Option B
Explanation:
If a pipe requires 'x' has to fill up the tank, then partly filled in 1 hr =[latex]\frac {1}{x}[/latex]
If pipe A requires 12 hrs to fill the tank, then partly filled by pipe A in 1 hr =[latex]\frac {1}{12}[/latex]
If pipe B requires 36 hrs to fill the tank, then part filled by pipe B 1 hr = [latex]\frac {1}{36}[/latex]
Hence, part filled by (A + B) together in 1 hr =[latex]\frac {1}{12} + \frac {1}{36}[/latex]
= [latex]\frac {48}{432}[/latex]= [latex]\frac {1}{9}[/latex]
In 1 hr both pipes together fill [latex]\frac {1}{9}[/latex]th part of the tank. This means, together they fill the tank in 9 hrs.
2. An electric pump can fill a tank in 4 hours. Due to leakage in the tank, it took 4[latex]\frac {1}{2}[/latex] has to fill the tank. If the tank is full, how much time will the leak take to empty the full tank?
A. 8 hrs
B. 16 hrs
C. 21 hrs
D. 36 hrs
Answer: Option D
Explanation:
Consider a pipe fills the tank in 'x' hrs. If there is a leakage in the bottom, the tank is filled in 'y' hrs.
The time is taken by the leak to empty the full tank = [latex]\frac {xy}{y – x}[/latex] hrs
Time taken to empty the tank by the leak = 4 x (9/2) / (9/2 ) - 4 = (36/2 ) / ½ = 18/ ½ = 18 x 2 = 36 hrs
3. Two pipes can fill a tank in 8 hrs & 6 hrs respectively. If they are opened on alternate hours and if pipe A gets opened first, then in how many hours, the tank will be full?
A. 6 hrs
B. 7 hrs
C. 8 hrs
D. 14 hrs
Answer: Option B
Explanation:
Pipe A's work in 1 hr = 1/8
Pipe B's work in 1 hr = 1/6
Pipes (A+B)'s work in first 2 hrs when they are opened alternately = 1/8 + 1/6 = 7 /24
Now,
In 4 hrs they fill : 2 X (7/24) = 7/12
In 6 hrs they fill : 3 X (7/24) = 7/8
After 6 hrs, part left empty = 1/8
Now it is A's turn to open up.
In one hr it fills 1/8 of the tank.
So, the tank will be full in = 6 hrs + 1 hr = 7 hrs.
Boats and Streams
1. If a boat travels with a speed of 10 km/hr in still water and the speed of the stream is 5 km/hr, what would be the time taken by boat to go 60 km downstream?
A. 2 hrs
B. 4 hrs
C. 6 hrs
D. 8 hrs
Answer: OptionB
Explanation:
In downstream, water stream increases the speed of the boat as they both are along the same directions. Hence, both the speeds are added.
Thus, Downstream speed (Sd) = (x + y) km/hr --------------(1)
Time = [latex]\frac {Distance}{Speed}[/latex] ------------------------------ (2)
By substituting the values of 'x' & 'y' in equation (1), we get
= 10 + 5 = 15 km/hr
We have,
Time = [latex]\frac {Distance}{Speed}[/latex]
Time taken by a boat to travel 60 km downstream will be equal to the ratio of distance traveled to the downstream speed.
Time taken by a boat =[latex]\frac {60}{15}[/latex] = 4 hours.
2. The speed of swimmer along with the flow of river is 40 km/hr and against the flow of river is 22 km/hr. What would be the speed of swimmer in still water?
A. 11 km/hr
B. 31 km/hr
C. 55 km/hr
D. 62 km/hr
Answer: Option B
Explanation:
In still water, we know that
Speed of boat (x) = ([latex]\frac {1}{2}[/latex]) x [Downstream speed(Sd) + Upstream speed(Su)]
With the given parameters like SD = 40 km/hr & SU = 22 km/hr, on substituting these values in above equation, we obtain
x = [latex]\frac {1}{2}[/latex] [SD + SU] = [latex]\frac {1}{2}[/latex] [40 + 22] = 31 km/hr
Numbers
1. If 6 + 12 + 18 + 24 + --- = 1800, then find the number of terms in the series.
Answer: Option D
Explanation:
This is an Arithmetic Progression, in which x = 6, y = 6, sum of terms = 1800
Sum of n terms =[latex]\frac {n}{2}[/latex][2x + (n – 1)y]
Substituting the given values, we get
1800 = [latex]\frac {n}{2}[/latex] [2 × 6 + (n – 1)6]
Solving we get,
1800 = 3n (n + 1)
n(n +1) = 600
n[latex]^{2}[/latex] + n = 600
25 × 24 = 600
Therefore,
n[latex]^{2}[/latex] + 25n – 24n – 600 = 0
(n + 25) (n – 24) = 0
24 and -25 are the two solutions obtained. Only positive value can be considered. Hence, n = 24
The number of terms in the series = 24
2. Find the largest 4 digit number which is divisible by 88.
A. 8844
B. 9999
C. 9944
D. 9930
Answer: Option C
Explanation:
We know that the largest 4 digit number is 9999.
Simply divide 9999 by 88.
After dividing 9999 by 88 we get, 55 as remainder.
The number is said to be completely divisible, only if the remainder is zero.
Hence, we can find the required answer by subtracting the remainder obtained from the 4 digit number.
Therefore, required number = 9999 – 55 = 9944
Partnership
1. Harry, John, and Smith start a shop by investing Rs. 27,000. Rs. 72,000 and Rs. 81,000 respectively. At the end of the year, the profit was distributed among them and Smith earns the share of Rs. 36,000. Find the total profit.
A. Rs. 1,10,000
B. Rs. 1,2,5000
C. Rs. 98,000
D. Rs. 80,000
Answer: Option D
Explanation:
Ratio of shares of Harry, John and Smith = Ratio of their investments
Harry : John : Smith = 27000 : 72000 : 81000 = 3 : 8 : 9
Given: Share of profit earned by Smith = Rs. 36,000
Total no. of shares = 3 + 8 + 9 = 20 shares
Smith’s share =[latex] \frac {9}{20}[/latex]
Let total profit = Rs. X
[latex] \frac {36000}{X}[/latex] = [latex] \frac {9}{20}[/latex]
X =[latex] \frac {36000 \times 20}{9}[/latex] = 80000
Total profit = Rs. 80,000
2. Two partners X and Y started a business by investing in the ratio of 5 : 8. Z joined them after 8 months investing an amount equal to that of Y. At the end of the year, 20 % profit was earned which is equal to Rs. 98,000. Find the amount invested by Z.
A. Rs. 213818.16
B. Rs. 223878.12
C. Rs. 203818.16
D. Rs. 219818.13
Answer: Option A
Explanation:
Let the total profit be p.
Given: 20 % profit is equal to Rs. 98,000
20 % of p = 98000
p = 490000
Capital of X = 5 x
Capital of Y = 8 x
Capital of Z = 8 x
Therefore,
(5x × 12) + (8x × 12) + (8x + 8) = 490000 × 12
220x = 5880000
x = Rs. 26727.27
We have find the amount invested by z.
8x = 8 x 26727.27 = Rs. 213818.16
Ratio and Proportion
1. If A : B : C = 3 : 4 : 7, then what is the ratio of (A / B) : (B / C) : (C / A)?
A. 63: 48: 196
B. 66: 49: 190
C. 56: 40: 186
D. 46: 38: 160
Answer: Option A
Explanation:
If a = kb for some constant k, then we can say that a is directly proportional to b.
A : B : C = 3 : 4 : 7
Assume, A = 3 k, B = 4 k, C = 7 k
Therefore,
[latex]\frac {A}{B}[/latex] = [latex]\frac {(3k)}{(4k)}[/latex] ,[latex]\frac {B}{C}[/latex] = [latex]\frac {(4k)}{(7k)}[/latex] , [latex]\frac {C}{A}[/latex] = [latex]\frac {(7k)}{(3k)}[/latex]
[latex]\frac {A}{B}[/latex] = [latex]\frac {(3)}{(4)}[/latex],[latex]\frac {B}{C}[/latex] = [latex]\frac {(4)}{(7)}[/latex], [latex]\frac {C}{A}[/latex] = [latex]\frac {(7)}{(3)}[/latex]
L.C.M of 3, 4, 7 is 84
(3 x 84) / 4 = 63
(4 x 84) / 7 = 48
(7 x 84) / 3 = 196
Ratio of (A/B) : (B/C) : (C/A) = 63:48:196
2. If Suresh distributes his pens in the ratio of 1/2: 1/4: 1/5: 1/7 between his four friends A, B, C, and D, then find the total number of pens Suresh should have?
A. 153
B. 150
C. 100
D. 125
Answer: Option A
Explanation:
A : B : C : D = [latex]\frac {1}{2}[/latex] : [latex]\frac {1}{4}[/latex] : [latex]\frac {1}{5}[/latex] : [latex]\frac {1}{7}[/latex]
1. L.C.M of 2, 4, 5, 7 is 140
2. Find the number of pens each friend received --------- (To find no. of pens each friend has, multiply the ratio with the L.C.M. calculated)
A = (1/2) x 140 = 70
B = (1/4) x 140 = 35
C = (1/5) x 140 = 28
D = (1/7) x 140 = 20
3. Total number of pens = (70 x + 35 x + 28 x + 20 x) = 153 x
Minimum number of pens (x) = 1
Therefore, total number of pens = 153 pens.
Problems on H.C.F and L.C.M
1. Find the largest number of 4-digits divisible by 12, 15 and 18.
A. 9900
B. 9750
C. 9450
D. 9000
Answer: Option A
Explanation:
The largest 4-digit number is 9999.
Remember: The question may be asked in a tricky way. Here, largest number does not mean H.C.F.. We have to find a number which is divisible by 12, 15 and 18
Required largest number must be divisible by the L.C.M. of 12, 15 and 18
L.C.M. of 12, 15 and 18
12 = 2 × 2 × 3
15 =5 × 3
18 = 2 × 3 × 3
L.C.M. = 180
Now divide 9999 by 180, we get remainder as 99
The required largest number = (9999 – 99) =9900
Number 9900 is exactly divisible by 180.
2. Find L.C.M. of 1.05 and 2.1
A. 1.3
B. 1.25
C. 2.1
D. 4.30
Answer: Option C
Explanation:
If numbers are in decimal form, convert them without decimal places. Therefore, the numbers are 105 and 210.
L.C.M. = 5 x 7 x 3 x 2 = 210
L.C.M. of 105 and 210 = 210
In decimal form: L.C.M. = 2.1
Banker’s Discount
1. Find the banker’s gain, if the present worth of a certain amount is Rs.2400 and the true discount is Rs.120.
Answer:Option C
Explanation:
Banker's Gain = [latex]\frac {(T.D.)^{2}}{P.W.}[/latex]
= [latex]\frac {(120)^{2}}{2400}[/latex] = Rs.6
2. The banker’s gain on a bill due 2 years hence at 10% per annum is Rs.10. What is the true discount?
Answer: Option B
Explanation:
T.D. = ([latex]\frac {B.G \times 100}{R \times T}[/latex])
= ([latex]\frac {10 \times 100}{10 \times 2}[/latex])
=Rs. 50
Compound Interest
1. The value of a sewing machine depreciates at the rate of 10 % after every year. If at the end of 3 years, its value is Rs. 8748, then find its purchase price.
A. 8000
B. 10000
C. 12000
D. 15000
Answer: Option C
Explanation:
If the cost of a machine is P1 and it decreases by R % annually, then the purchase price after n years is given by:
P2 =P1 [latex](1 - \frac {R}{100})^{n}[/latex]
We are given that the value of a sewing machine depreciates at the rate of 10 % after every year. After 3 years, its value is Rs. 8748.
8748 =P1 [latex](1 - \frac {10}{100})^{3}[/latex]
P1 =Rs.12000
The purchase price of the sewing machine = Rs. 12000
2. Find the compound interest on Rs. 20,000 in 2 years at 4 % per annum, the interest being compounded half-yearly.
A. Rs. 1648.64
B. Rs. 1596.32
C. Rs. 14826.56
D. Rs. 11563.99
Answer: Option A
Explanation:
Interest is compounded half-yearly, therefore,
Amount = P [latex](1 + \frac {(R/2)}{100})^{2n}[/latex] - - - - - - - - - [Interest compounded Half-yearly]
Given: Principal = Rs. 20000, Rate = 2 % per half-year, Time = 2 years = 4 half- years
Amount = 20000 [latex](1 + \frac {(2)}{100})^{4}[/latex]
Amount=Rs.21648.64
Compound Interest = Total amount – Principal
= 21648.64 – 20000
= Rs. 1648.64
Area
1. When folded into two equal halves a rectangular sheet had a perimeter of 48cm for each part folded along one set of sides and the same is 66cm when folded along the other set of sides. Find the area of the sheet.
A. 1584
B. 1120
C. 792
D. 1320
Answer: Option B
Explanation:
Let the sheet be folded along its breadth and its perimeter = 48cm
Therefore, (l/2 + b) = 48 …... (i)
Now, let the sheet be folded along its length, and the perimeter = 66cm
(l + b/2)= 66 …... (ii)
Solving (i) and (ii), we get,
l = 56cm, b = 20cm
Area = l X b
Area = 1120 cm[latex]^{2}[/latex]
2. If the length is increased by 25%, by what percent the width of a rectangle should be decreased so as to keep the area the same.
A. 25%
B. 20%
C. 30%
D. 10%
Answer: Option B
Explanation:
Let the original length be l, and the width be b
Therefore, the area = l X b
Now, as the length is increased by 25%, the new length is (1.25 X l) and let the new width be x.
As the area is same, 1.25 X l X x = l X b
x = b/1.25 = 0.8b
Therefore, the width is to be decreased by 20%.
Time and Work
1. Two painters 'P1' & 'P2' paint the bungalow in 3 days. If P1 alone can paint the bungalow in 12 days, in how many days can 'P2'' alone complete the same paint work?
A. 4 days
B. 6 days
C. 9 days
D. 12 days
Answer: Option A
Explanation:
If a person can do a part of work in 'n' days, the person's work in 1 day =[latex]\frac {1}{n}[/latex]
As painters, P1 & P2 paint the bungalows in 3 days, then work done by both painters = [latex]\frac {1}{3}[/latex]
As P1 paint it alone in 12 days, then work done by painter P1 = [latex]\frac {1}{12}[/latex]
Work was done by painter P2 =[latex]\frac {1}{3}[/latex] – [latex]\frac {1}{12}[/latex]
= [latex]\frac {4 - 1}{12}[/latex] = [latex]\frac {3}{12}[/latex] = [latex]\frac {1}{4}[/latex]
Therefore, the same work will be completed by painter P2 in 4 days.
2. Pooja is twice as efficient as Aarti and takes 90 days less than Aarti to complete the job. Find the time in which they can finish the job together.
A. 30 days
B. 45 days
C. 60 days
D. 90 days
Answer: Option C
Explanation:
Since 'A' is 'm' times as efficient as 'B' & takes 'D' days less than 'B', then the time required to complete the job together is given by,
T = m x [latex]\frac {D}{(m^{2}– 1)}[/latex]
T = 2 x [latex]\frac {90}{(2^{2}– 1)}[/latex] = [latex]\frac {180 }{3}[/latex] = 60 days
Allegation or Mixture
1. In what ratio must wheat A at Rs. 10.50 per kg be mixed with wheat B at Rs. 12.30 per kg, so that the mixture be worth of Rs. 11 per kg?
A. 13: 5
B. 18 : 3
C. 17: 5
D. 11: 5
Answer: Option A
Explanation:
Convert Rs into paise, to make the calculation easy
Ratio =[latex]\frac {(B – M)}{(M – A)}[/latex]
The required ratio = 130 : 50 = 13 : 5
2. A shopkeeper has 100 kg of salt. He sells part of the total quantity A at 7% profit and the rest B at 17 % profit. If he gains 10 % profit on the whole quantity, then find how much is sold at 7 % profit?
A. 30 kg
B. 35 kg
C. 40 kg
D. 45 kg
Answer: Option A
Explanation:
Assume that A and B are two parts of the mixture. To determine the quantity A and B, first calculate the ratio of A: B.
Given:
1) The selling price of the mixture with 10% profit = Rs. 110
2) With a 17 % profit, the selling price of A = Rs. 117
3) With 7 % profit, the selling price of B = Rs. 107
Now, this question can be easily solved by using the rule of the allegation
Now, the ratio of A: B = 3: 7
Let the quantity of part A be 3x and part B be 7x in the total quantity of 100 kg.
Therefore, 3x + 7x = 100
10x = 100
x = 10
Quantity of part A = 3x = 3 x 10 = 30 kg
Quantity of part B = 7x = 7 x 10 = 70 kg
Decimal Fraction
1. Convert 0.737373… into a vulgar fraction?
A. [latex]\frac {73}{99}[/latex]
B. [latex]\frac {73}{100}[/latex]
C. [latex]\frac {73}{90}[/latex]
D. [latex]\frac {73}{900}[/latex]
Answer: Option A
Explanation:
In a decimal fraction, if there are n numbers of repeated numbers after a decimal point, then just write one repeated number in the numerator and in denominator take n number of nines equal to repeated numbers you observe after the decimal point.
0.737373… is written as 0.[latex]\overline{73}[/latex]
Numerator = 73 ---- (one repeated number)
Denominator = 99 ---- (73 is the number which is repeated)
Vulgar fraction = [latex]\frac {73}{99}[/latex]
2. If [latex]\frac {347.624}{0.0089}[/latex] = a, then find the value of [latex]\frac {347624}{0.0089}[/latex] = ?
A. [latex]\frac {a}{10}[/latex]
B. 10 a
C. [latex]\frac {a}{1000}[/latex]
D. 1000a
Answer: Option C
Explanation:
Given:[latex]\frac {347.624}{0.0089}[/latex] = a
The value of [latex]\frac {347624}{0.0089}[/latex] ÷ 1000 = a ÷ 1000 = [latex]\frac {a}{1000}[/latex]
Probability
1. Tickets numbered 1 to 50 are mixed and one ticket is drawn at random. Find the probability that the ticket drawn has a number which is a multiple of 4 or 7?
A. 9/25
B. 9/50
C. 18/25
D. None of these
Answer: Option A
Explanation:
S = {1, 2, 3, … , 49, 50}
E = {4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 7, 14, 21, 35, 42, 49}
n(S) = 50
n(E) = 18
P(E) = n(E)/n(S) = 18/50
= 9/25
2. From a pack of 52 cards, one card is drawn at random. Find the probability that the drawn card is a club or a jack?
A. 17/52
B. 8/13
C. 4/13
D. 1/13
Answer: Option C
Explanation:
n(S) = 52
n(E) = 16
P(E) = n(E) / n(S) = 16/ 52
= 4/13
Average
1. Find the average of all numbers between 5 and 49 which are divisible by 5.
Answer: Option B
Explanation:
The numbers divisible by 5 are: 5, 10, 15, 20, 25, 30, 35, 40, 45.
Average = [latex]\frac {Sum of Quantities}{Number of Quantities}[/latex] = [latex]\frac {(5 + 10 + 15 + 20 + 25 + 30 + 35 + 40 + 45)}{9}[/latex] = [latex]\frac {225}{9}[/latex] = 25
2. The average of 15 numbers is 15. If the average of first five numbers is 14 and that of other 9 numbers is 16, then find the middle number.
Answer: Option B
Explanation:
Given: Average of 15 numbers = 15, Average of 5 numbers = 14, Average of 9 numbers = 16
Average = [latex]\frac {Total Numbers}{No. of Numbers}[/latex]
15 = [latex]\frac {Total Numbers}{15}[/latex]
Therefore, total numbers = 15 x 15 = 225
Middle number = (Total numbers) – [(Average of 5 num x no of num) + ( Average of 9 num x no of num)]
= (225) – [(14 x 5) + (16 x 9)]
= (225) – [214]
= 11
Therefore, the middle number is 11
3. In a school, average marks of three batches of 40, 50 and 60 students respectively is 45, 55 and 70. Find the average marks of all the students.
A. 54.78
B. 55.23
C. 50.36
D. 58.33
Answer: Option D
Explanation:
We know,
Average = [latex]\frac {Sum of Quantities}{Number of Quantities}[/latex]
Here,
Number of quantities = Number of students in each batch
As average marks of students are given, calculate total marks of each batch first. So total marks for
Batch 1 = (40 x 45) = 1800
Batch 2 = (50 x 55) = 2750
Batch 3 = (60 x 70) = 4200
Sum of marks = (1800 + 2750 + 4200) = 8750
Therefore,
Required Average =[latex]\frac {(Sum of Works)}{(Total No. of Students in each batch)}[/latex] = [latex]\frac {(8750)}{(40 + 50 + 60)}[/latex] = 58.33
Stocks and Share
1. Find the number of shares that can be bought for Rs.8200 if the market value is Rs.20 each with brokerage being 2.5%.
A. 450
B. 500
C. 400
D. 410
Answer: Option C
Explanation:
Cost of each share = (20 + 2.5% of 20) = Rs.20.5
Therefore, number of shares = 8200/20.5 = 400
2. Find the market value of the stock if 6% yields 10%.
Answer: Option A
Explanation:
Let the investment be Rs.100 for an income of Rs.10
Therefore, for an income of Rs.6, the investment = 600/10 = Rs.60
Square Root and Cube Root
1. Find the square root of 5929
Answer: Option C
Explanation:
Remember the trick discussed in Quick Tips and Tricks
Step 1: Split the number 59 29
7[latex]^{2}[/latex] = 49 is the nearest number to 59.Hence, the digit in ten’s place is 7.
Step 2: Last digit of number 29 is 9. Therefore, 3 or 7 are the digits in unit’s place.
Multiply 3 by next consecutive higher number i.e. 4
3 × 4 = 12
But 12 < 59, hence consider the largest number among 3 and 7.
The digit in unit’s place is 7.
Hence, the square root of 5929 is 77
2. 28[latex]\sqrt {x}[/latex] + 1426 = [latex]\frac {3}{4}[/latex]of 2984. Find x
A. 659
B. 694
C. 841
D. 859
Answer: Option C
Explanation:
28[latex]\sqrt {x}[/latex] + 1426 = [latex]\frac {3}{4}[/latex]of 2984.
28[latex]\sqrt {x}[/latex] + 1426 = [latex]\frac {3}{4}[/latex]× 2984= 2238
28[latex]\sqrt {x}[/latex] = 2250 – 1426 = 812
[latex]\sqrt {x}[/latex] = 29
x = 841
Problems on Ages
1. What is John’s present age, if after 10 years his age will be 5 times his age 5 years back.
A. 6.2 years
B. 7.7 years
C. 8.7 years
D. 10 years
Answer: Option C
Explanation:
1) Let John’s present age be x
2) John’s age before 5 years = (x - 5)
3) John’s age after 10 years = (x + 10)
We are given that, John’s age after 10 years (x + 10) is 5 times his age 5 years back (x – 5)
Therefore,
(x + 10) = 5 (x – 5)
Solving the equation, we get
x + 10 = 5x – 25
4x = 35
x = 8.75 years
2. One year ago, the ratio of Harry and Peter age’s was 5: 6 respectively. After 4 years, this ratio becomes 6: 7. How old is Peter?
A. 25 years
B. 26 years
C. 31 years
D. 35 years
Answer: Option C
Explanation:
If ages in the numerical are mentioned in ratio A: B, then A: B will be Ax and Bx.
We are given that age ratio of Harry : Pitter = 5 : 6
1) Harry’s age = 5x and Peter’s age = 6x
2) One year ago, their age was 5x and 6x. Hence at present, Harry’s age = 5x +1 and Peter’s age = 6x +1
3) After 4 years,
Harry’s age = (5x +1) + 4 = (5x + 5)
Peter’s age = (6x +1) + 4 = (6x + 5)
4) After 4 years, this ratio becomes 6 : 7. Therefore,
[latex]\frac {Harry’s Age}{6}[/latex] = [latex]\frac {Peter’s Age}{7}[/latex]
(5x + 5) / (6x + 5) = 6 / 7
7 (5x + 5) = 6 (6x + 5)
X = 5
Peter’s present age = (6x + 1) = (6 x 5 + 1) = 31 years
Harry’s present age = (5x + 1) = (5 x 5 + 1) = 26 years