1. A sum of Rs. 36.90 is made up of 180 coins which are either 10 paise coins or 25 paise coins. The number of 10 p coins is
A. 48
B. 54
C. 56
D. 60
E. None of these
2. The present age of a father is 20 years less than three times his son’s age. If the present age of the son, in years is an integer, which of the following choices represent the present age of the father?
A. 53
B. 38
C. 48
D. 27
E. 55
3. A started a business with investing Rs. 8000 and after some months, B joined with investing Rs. 5000. At the end of one year, total profit was Rs. 4250 and share of A is Rs. 3000. After how many months did B join?
Directions[4-5]: In the following number series only one number is wrong. Find out the wrong number.
4. 15, 18, 23, 30, 38, 50
A. 23
B. 38
C. 30
D. 50
E. 60
5. 4, 2.5, 3.5, 6.5, 15.5, 41.25, 126.75
A. 2.5
B. 3.5
C. 6.5
D. 15.5
E. 14
Answers and Explanations
1. Answer - Option B
Explanation -
Let x be number of 10p coins and y be number of 25p coins
Then, ATP:
x + y = 180 --------------------(i)[As total number of coins is 180]
10x + 25y = 36.9Rs = 3690p ----(ii)[As 10p coins and 25p coins make the sum = Rs. 36.90]
Solving equation (i) and (ii)
We get:
x = 54 and y = 126
So number of 10p coins = 54
2. Answer - Option E
Explanation -
Let the present ages of the father and the son be f and s respectively.
F = 3s - 20
s = [latex]\frac {(f+20)}{3}[/latex]
As s is an integer, so f+20 is divisible by 3. Going by the choices it must be 55 years.
3. Answer - Option A
Explanation -
A started a business with investing Rs. 8000 and after some months, B joined with investing Rs. 5000.
Equivalent capital of A
= Rs. 8000 × 12
= Rs. 96000
Let B joined after x months.
So, equivalent capital of B
= Rs. 5000 × (12 – x)
= Rs. 60000 – 5000x
Total profit after one year = Rs. 4250
Share of A = Rs. 3000. Then, the share of B = Rs. 4250 – 3000 = Rs. 1250
So, the ratio of their share;
A : B = 3000 : 1250 = 12 : 5
Now, we can write,
[latex] \frac {96000}{(60000 – 5000x)} = \frac {12}{5}[/latex]
⇒ 60000 – 5000x = 96000 × [latex] \frac {5}{12}[/latex]
⇒ 60000 – 5000x = 8000 × 5
⇒ 5000x = 60000 – 40000
⇒ x = [latex] \frac {20000}{5000}[/latex]
⇒ x = 4
∴ After 4 months, B joined in the business.
4. Answer - Option B
Explanation -
difference is odd number series:
+3, +5, +7, +9, +11
so series 15, 18, 23, 30, 39, 50
5. Answer - Option C
Explanation -
The pattern of the number series is:
4 × 0.5 + 0.5 = 2 + 0.5 = 2.5
2.5 × 1 + 1 = 3.5
3.5 × 1.5 + 1.5 = 6.75 ≠6.5
6.75 × 2 + 2 = 15.5
15.5 × 2.5 + 2.5 = 38.75 + 25 = 41.25
41.25 × 3 + 3 = 123.75 + 3 = 126.75