question: X can finish a work in 18 days. Y can finish the same work in 15 days. Yworked for 10 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 1
(B) 3
(C) 6
(D) 8
(E) 9
answer: Stream of consciousness: Work done by X in 1 day = 1/18
Work done by Y in 1 day = 1/15
Work done by Y in 10 days = 10/15 = 2/3
Remaining work = 1 2/3 = 1/3
Number of days in which X can finish the remaining work = (1/3) / (1/18) = 6 The answer is (C).

q: 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
a: Stream of consciousness: (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: What is the difference between 80% of 170 and 35% of 300.
Options:
(A) 30
(B) 29
(C) 37
(D) 36
(E) 31
answer: Stream of consciousness: (80/100) * 170 (35/100) * 300
136 - 105 = 31 The answer is (E).

q: The speed of a train is 90 kmph. What is the distance covered by it in 20 minutes?
Options:
(A) 15
(B) 66
(C) 77
(D) 30
(E) 42
a: Stream of consciousness: 90 * 20/60 = 30 kmph The answer is (D).

question: A train traveling at 72 kmph crosses a platform in 30 seconds and a man standing on the platform in 19 seconds. What is the length of the platform in meters?
Options:
(A) 220 meters
(B) 360 meters
(C) 420 meters
(D) 600 meters
(E) Cannot be determined
answer: Stream of consciousness: Speed of the train in metres/sec = 72000/3600 = 20
Distance travelled by train to cross the platform = 30 * 20 = 600 = Length of train + Length of platform
Distance travelled by train to cross the man = 19 * 20 = 380 = Length of train
Length of platform = 600 - 380 = 220 The answer is (A).

question: A card shop contains 5 birthday cards, 4 holiday cards, and 3 graduation cards. If three cards are purchased at random from the shop, what is the probability that the three cards will be graduation cards?
Options:
(A) 1/33
(B) 6/264
(C) 1/44
(D) 1/264
(E) 1/1320
answer:
Stream of consciousness: It doesn't matter which type of card you choose, so:
Probability of choosing 1st card: 3/12
Probability of choosing 2nd card of the same type: 2/11
Probability of choosing 3rd card of the same type: 1/10
Multiply and you get 1/264 The answer is (D).