Question: A man, a woman and a boy can complete a job in 3, 4 and 12 days respectively. How many boys must assist 1 man and 1 woman to complete the job in 1/4 of a day?
Options:
(A) 22
(B) 66
(C) 28
(D) 41
(E) 61
Answer: (1 man + 1 woman)'s 1 day work = (1/3 + 1/4) = 7/12 Work done by 1 man and 1 woman in 1/4 day = (7/12 * 1/4) = 7/48
Remaining work = (1 - 7/48) = 41/48
Work done by 1 boy in 1/4 day = ( 1/12 * 1/4) = 1/48
Number of boys required = 41/48 * 41 = 41.
The answer is (D).

Question: The speed of a train is 90 kmph. What is the distance covered by it in 10 minutes?
Options:
(A) 15
(B) 66
(C) 77
(D) 52
(E) 42
Answer: 90 * 10/60 = 15 kmph
The answer is (A).

Question: A wheel rotates 20 times every minute and moves 15 cm during each rotation. How many metres does the wheel move in one hour?
Options:
(A) 6 metre
(B) 18 metre
(C) 180 metre
(D) 1200 metre
(E) 130 metre
Answer: Number of times wheel moves in 1 hour = 12 * 60 = 1200
:. Distance moves = (1200*15) cms = 18000 cms
In metres = 180 metre
The answer is (C).

Question: Simple interest on a certain sum is 16 over 25 of the sum. Find the rate per cent and time, if both are equal.
Options:
(A) 8% and 8 years
(B) 6% and 6 years
(C) 10% and 10 years
(D) 12 % and 12 years
(E) None of these
Answer:
1625P = PRR/100
R2 = 160025 R = 405 = 8%
Also, time = 8 years
The answer is (A).