q: A train 180 m long running at 70 kmph crosses a platform in 20 sec. What is the length of the platform?
Options:
(A) 208
(B) 277
(C) 350
(D) 881
(E) 271
a: Stream of consciousness: D = 70 * 5/18 = 20 = 388 180 = 208 The answer is (A).

question: Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes and 10 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P, Q and R respectively. What is the proportion of solution P in the liquid in the tank after 3 minutes?
Options:
(A) 3/11
(B) 2/11
(C) 1/11
(D) 4/11
(E) 1/11
answer: Stream of consciousness: Part filled by (A + B + C) in 3 minutes = 3(1/30 + 1/20 + 1/10) = 11/20
Part filled by A in 3 minutes = 3/30
Required ratio = 3/30 * 20/11 = 2/11 The answer is (B).

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 running at the speed of 60 km/hr crosses a pole in 6 sec. What is the length of the train?
Options:
(A) 287
(B) 699
(C) 677
(D) 168
(E) 100
answer: 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 (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).

q: Two trains are moving at 80 kmph and 70 kmph in opposite directions. Their lengths are 150 m and 100 m respectively. The time they will take to pass each other completely is?
Options:
(A) 6 sec
(B) 7 sec
(C) 7 2/2 sec
(D) 8 sec
(E) 9 sec
a:
Stream of consciousness: 70 + 80 = 150 * 5/18 = 125/3 mps
D = 150 + 100 = 250 m
T = 250 * 3/125 = 6 sec The answer is (A).