q: X can finish a work in 21 days. Y can finish the same work in 15 days. Y worked for 5 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 12
(B) 13
(C) 16
(D) 14
(E) 18
a: Stream of consciousness: Work done by X in 1 day = 1/21
Work done by Y in 1 day = 1/15
Work done by Y in 5 days = 5/15 = 1/3
Remaining work = 1 1/3 = 2/3
Number of days in which X can finish the remaining work = (2/3) / (1/21) = 14 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 17 seconds. What is the length of the platform in meters?
Options:
(A) 240 meters
(B) 260 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 = 17 * 20 = 340 = Length of train
Length of platform = 600 - 340 = 260 The answer is (B).

q: A train running at the speed of 60 km/hr crosses a pole in 6 sec. What is the length of the train?
Options:
(A) 100 m
(B) 190 m
(C) 115 m
(D) 110 m
(E) 150 m
a: Stream of consciousness: Speed = 60 * 5/18 = 50/3 m/sec
Length of the train = speed * time = 50/3 * 6 = 100 m The answer is (A).

question: A person spends 1/3rd of the money with him on clothes, 1/5th of the remaining on food and 1/4th of the remaining on travel. Now, he is left with Rs 200. How much did he have with him in the beginning?
Options:
(A) s 200
(B) s 500
(C) s 300
(D) s 450
(E) s 550
answer: Stream of consciousness: Suppose the amount in the beginning was Rs 'x'
Money spent on clothes = Rs 1x/3 Balance = Rs 2x/3
Money spent on food = 1/5 of 2x/3 = Rs 2x/15
Balance = 2x/3 - 2x/15 = Rs 8x/15
Money spent on travel = 1/4 of 8x/15 = Rs 2x/15 = 8x/15 - 2x/15 = 6x/15 = Rs2x/5
Therefore 2x/5 = 200 = 500 The answer is (B).

q: Two trains are traveling on parallel tracks in the same direction. The faster train travels at 130 miles per hour, while the slower train travels at 80 miles per hour. At 2 o'clock the faster train is 20 miles behind the slower one. How far apart are the two trains at 5 o'clock?
Options:
(A) 60 miles
(B) 80 miles
(C) 90 miles
(D) 130 miles
(E) 400 miles
a: Stream of consciousness: Answer = D. 130 miles
Relational speed = 130 - 80 = 50 miles per hour
In 3 hours, difference = 50 * 3 = 150 miles
Fast train trailing 20 miles, so effective difference = 150 - 20 = 130 miles The answer is (D).

q: The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?
Options:
(A) 9
(B) 8
(C) 7
(D) 6
(E) 2
a:
Stream of consciousness: 1 to 9 = 9 * 9 = 81
1 to 5 = 5 * 10 = 50
5 to 9 = 5 * 8 = 40
5th = 50 + 40 = 90 81 = 9 The answer is (A).