Simple and Compound Interest
1. A sum of Rs. 25000 becomes Rs. 27250 at the end of 3 years when calculated at simple interest. Find the rate of interest.
Answer: Option (C)
Explanation:
Simple interest = 27250 – 25000 = 2250
Time = 3 years.
SI = PTR / 100 → R = SI * 100 / PT
R = 2250 * 100 / 25000 * 3 → R = 3%.
2. Find the present worth of Rs. 78000 due in 4 years at 5% interest per year.
A. 50000
B. 60000
C. 55000
D. 65000
Answer: Option (D)
Explanation:
Amount with interest after 4 years = Rs. 78000
Therefore, simple interest = 78000 – Principal.
Let the principal amount be p.
78000 – p = p*4*5/100 → p=13000
Principal = 78000 – 13000 = Rs. 65000.
3. A certain principal amounts to Rs. 15000 in 2.5 years and to Rs. 16500 in 4 years at the same rate of interest. Find the rate of interest.
A. 10%
B. 12%
C. 8%
D. 10%
Answer: Option (C)
Explanation:
Amount becomes 15000 in 2.5 years and 16500 in 4 years.
Simple interest for (4-2.5) years = 16500 – 15000
Therefore, SI for 1.5 years = Rs. 1500.
SI for 2.5 years = 1500/1.5 * 2.5 = 2500
Principal amount = 15000 – 2500 = Rs. 12500.
Rate of Interest = 2500 * 100 / 12500 * 2.5 → R = 8%.
4. How long will it take a certain amount to increase by 30% at the rate of 15% simple interest?
Answer: Option (A)
Explanation:
Let the principal be Rs. x
Simple interest = x*30/100 = 3x/10
T = 100*SI/PR = 100*3x/10 / x*15 = 2%
Alternatively, this can be solved by considering principal amount to be Rs. 100. Then simple interest becomes Rs. 30.
Then, T = 100*30/100*15 = 2%
5. A money lender lent Rs. 1000 at 3% per year and Rs. 1400 at 5% per year. The amount should be returned to him when the total interest comes to Rs. 350. Find the number of years.
A. 3.5
B. 3.75
C. 4
D. 4.5
Answer: Option (A)
Explanation:
(1000*t*3/100) + (1400*t*5/100) = 350 → t =3.5
Profit and Loss
1. A trader mixes 26 kg of rice at Rs. 20 per kg with 30 kg of rice of other variety at Rs. 36 per kg and sells the mixture at Rs. 30 per kg. His profit percent is:
A. No profit, no loss
B. 5%
C. 8%
D. 10%
Answer: Option (B)
Explanation:
C.P. of 56 kg rice = Rs. (26 x 20 + 30 x 36) = Rs. (520 + 1080) = Rs. 1600.
S.P. of 56 kg rice = Rs. (56 x 30) = Rs. 1680.
Gain =(80/1600*100) % = 5%.
2. If selling price is doubled, the profit triples. Find the profit percent?
A. 100%
B. 200%
C. 300%
D. 400%
Answer: Option (A)
Explanation:
Let the C.P be Rs.100 and S.P be Rs.x, Then
The profit is (x-100)
Now the S.P is doubled, then the new S.P is 2x
New profit is (2x-100)
Now as per the given condition;
=> 3(x-100) = 2x-100
By solving, we get
x = 200
Then the Profit percent = (200-100)/100 = 100
Hence the profit percentage is 100%
3. If books bought at prices ranging from Rs. 200 to Rs. 350 are sold at prices ranging from Rs. 300 to Rs. 425, what is the greatest possible profit that might be made in selling eight books?
A. 600
B. 1200
C. 1800
D. none of these
Answer: Option (C)
Explanation:
Least Cost Price = Rs. (200 * 8) = Rs. 1600.
Greatest Selling Price = Rs. (425 * 8) = Rs. 3400.
Required profit = Rs. (3400 - 1600) = Rs. 1800.
4. If the cost price is 25% of selling price. Then what is the profit percent.
A. 150%
B. 200%
C. 300%
D. 350%
Answer: Option (C)
Explanation:
Let the S.P = 100
then C.P. = 25
Profit = 75
Profit% = (75/25) * 100 = 300%
5. A man buys oranges at Rs 5 a dozen and an equal number at Rs 4 a dozen. He sells them at Rs 5.50 a dozen and makes a profit of Rs 50. How many oranges does he buy?
A. 30 dozens
B. 40 dozens
C. 50 dozens
D. 60 dozens
Answer: Option (C)
Explanation:
Cost Price of 2 dozen oranges Rs. (5 + 4) = Rs. 9.
Sell price of 2 dozen oranges = Rs. 11.
If profit is Rs 2, oranges bought = 2 dozen.
If profit is Rs. 50, oranges bought = (2/2) * 50 dozens = 50 dozens.
Elementary Algebra
1. What is the solution of the equations x - y = 0.9 and 11(x + y)[latex]^{-1}[/latex] = 2?
A. x = 3.2, y = 2.3
B. x = 1, y = 0.1
C. x = 2, y = 1.1
D. x = 1.2, y = 0.3
Answer: Option (A)
Explanation:
x - y = 0.9 ...(i)
and 11(x + y)[latex]^{-1}[/latex]=2
⇒ 11/ (x + y) = 2
⇒ 2(x + y) =11
⇒ x + y = 11/2 ...(ii)
On solving Eqs.(i) and (ii),we get
x = 3.2
and y = 2.3
2. The product of two alternate odd integers exceeds three times the smaller by 12. What is the larger integer?
Answer: Option (B)
Explanation:
Let two alternate odd integers odd integers be (2x+1) and (2x+5).
Then according to the question,
(2x + 1) (2x + 5) = 3(2x + 1) + 12
⇒ (2x + 1) (2x + 5 - 3) = 12
⇒ 2x[latex]^{2}[/latex] + 3x - 5 = 0
On solving this quadratic equation,we get
x = 1 and x = -5/2
x = -5/2 is not a integer ∴ x = 1
Then, larger integer = 2x + 5 = 2 x 1 + 5 = 7
3. The degree f polynomial p(x) = x[latex]^{3}[/latex] + 1 + 2x = 6x + 1/x is?
Answer: Option (B)
Explanation:
x[latex]^{3}[/latex] + 1 + 2x =6x + 1/x
x[latex]^{3}[/latex] + 1 + 2x = (6x[latex]^{2}[/latex] + 1)/x
(x[latex]^{3}[/latex] + 1 + 2x)x = 6x[latex]^{2}[/latex] + 1
x[latex]^{4}[/latex] - 4x[latex]^{2}[/latex] - 6x[latex]^{2}[/latex] -1 =0
x[latex]^{4}[/latex] - 4x[latex]^{2}[/latex] + x - 1 =0
Degree of polynomial is highest exponent degree term i.e.,4.
4. If a number is divided by 4, then 3 is subtracted, the result is 0. What is the number?
Answer: Option (A)
Explanation:
The correct answer is 12, because ( 12 / 4 ) - 3 = 0.
5. 16x - 8 =?
A. 8x
B. 8(2x-x)
C. 8(2x-1)
D. 8(2x-8)
Answer: Option (C)
Explanation:
The expression 16x - 8 may be factored as 8(2x - 1).
Geometry and Trigonometry
1. Sine rule for a triangle states that
A. a/sin A = b/sin B = c/sin C
B. sin A/a = sin B/b = sin C/c
C. a/sin A + b/sin B + c/sin C
D. 2a/sin A = 2b/sin B = 2c/sin C
Answer: Option (B)
2. Considering Cosine Rule of any triangle ABC, possible measures of angle A includes
A. angle A is acute
B. angle A is obtuse
C. angle A is right-angle
D. all of above
Answer: Option (D)
3. If cos 55[latex]^{0}[/latex] and sin 55[latex]^{0}[/latex] = 0.8 each then answer of cos 125[latex]^{0}[/latex] + 5 sin 55[latex]^{0}[/latex] is
A. 0.8
B. 2.4
C. 2.8
D. 3.2
Answer: Option (B)
4. How many tiles whose length and breadth are 12 cm and 5 cm respectively will be needed to fit in a rectangular region whose length and breadth are respectively 144 cm and 100 cm:
A. 160
B. 240
C. 320
D. 450
Answer: Option (B)
Explanation:
Total area of the region
=100×144
=14400 cm[latex]^{2}[/latex]
Area of one tile
=12×5
=60 cm[latex]^{2}[/latex]
Number of tiles required
=14400/60
=240
Therefore, 240 tiles are required.
5. A cone and a hemisphere have equal bases and equal volumes. Find the ratio of their heights.
A. 1:2
B. 2:1
C. 3:1
D. 3:4
Answer: Option (B)
Explanation:
Volume of the cone
=πr[latex]^{2}[/latex]h/3
=Volume of a hemisphere
=2πr[latex]^{3}[/latex]/3
⇒ Height of a hemisphere = Radius of its base
By the above formula, we can see that h:r = 2:1.
Elementary Statistics etc.
1. Marks obtained by an student in 5 subjects are given below 25, 26, 27, 28, 29 in these obtained marks 27 is
A. mode
B. median and mode
C. mean and median
D. both (A) and (C)
Answer: Option (C)
Explanation:
27 is in the middle, so is the median and its the mean too.
2. A dice is thrown 3 times .what is the probability that atleast one head is obtained?
A. 7/8
B. 6/8
C. 5/8
D. 9/8
Answer: Option (A)
Explanation:
Sample space = [HHH, HHT, HTH, THH, TTH, THT, HTT, TTT]
Total number of ways = 2 × 2 × 2 = 8. Fav. Cases = 7
P (A) = 7/8
OR
P (of getting at least one head) = 1 – P (no head)⇒ 1 – (1/8) = 7/8.
3. Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?
A. 1/2
B. 3/5
C. 9/20
D. 8/15
Answer: Option (C)
Explanation:
Here, S = {1, 2, 3, 4, ...., 19, 20}.
Let E = event of getting a multiple of 3 or 5 = {3, 6 , 9, 12, 15, 18, 5, 10, 20}.
P(E) = n(E)/n(S) = 9/20.
4. Two dice are tossed. The probability that the total score is a prime number is:
A. 5/12
B. 1/6
C. 1/2
D. 7/9
Answer: Option (A)
Explanation:
Clearly, n(S) = (6 x 6) = 36.
Let E = Event that the sum is a prime number.
Then E= { (1, 1), (1, 2), (1, 4), (1, 6), (2, 1), (2, 3), (2, 5), (3, 2), (3, 4), (4, 1), (4,3),(5, 2), (5, 6), (6, 1), (6, 5) }
n(E) = 15.
P(E) = n(E)/n(S) = 15/36 = 5/12.
5. A bag contains 6 black and 8 white balls. One ball is drawn at random. What is the probability that the ball drawn is white?
A. 3/7
B. 4/7
C. 1/8
D. 3/4
Answer: Option (B)
Explanation:
Let number of balls = (6 + 8) = 14.
Number of white balls = 8.
P (drawing a white ball) = 8 /14 = 4/7.