In what time will a railway train 40 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 3 sec
(B) 4 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec
Answer and stream of consciousness: (B)
Stream of consciousness: T = 40/36 * 18/5 = 4 sec

Pipes A and B can fill a cistern in 8 and 24 minutes respectively. They are opened an alternate minutes. Find how many minutes, the cistern shall be full?
Options:
(A) 11
(B) 12
(C) 99
(D) 75
(E) 72
Answer and stream of consciousness: (B)
Stream of consciousness: 1/8 + 1/24 = 1/6
6 * 2 = 12

10 books are placed at random in a shelf. The probability that a pair of books will always be together is?
Options:
(A) 1/0
(B) 1/3
(C) 1/5
(D) 1/2
(E) 1/1
Answer and stream of consciousness: (C)
Stream of consciousness: 10 books can be rearranged in 10! ways consider the two books taken as a pair then number of favourable ways of getting these two books together is 9! 2!
Required probability = 1/5

A train 200 meters long completely crosses a 300 meters long bridge in 45 seconds. What is the speed of the train is?
Options:
(A) 10
(B) 20
(C) 30
(D) 40
(E) 50
Answer and stream of consciousness:
(D)
Stream of consciousness: S = (200 + 300)/45 = 500/45 * 18/5 = 40