Q: 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
A: OK... Stream of consciousness: T = 40/36 * 18/5 = 4 sec
The answer is (B).

Q: 10 books are placed at random in a shelf. The probability that a pair of books will always be together is?
Options:
(A) 1/6
(B) 1/7
(C) 1/5
(D) 1/9
(E) 1/2
A: OK... 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
The answer is (C).

Q: The average of first 10 odd numbers is?
Options:
(A) 11
(B) 10
(C) 99
(D) 77
(E) 65
A: OK... Stream of consciousness: Sum of 10 odd no. = 100
Average = 100/10 = 10
The answer is (B).

Q: The speed of a boat in still water is 70kmph and the speed of the current is 20kmph. Find the speed downstream and upstream?
Options:
(A) kmph
(B) kmph
(C) kmph
(D) kmph
(E) kmph
A:
OK... Stream of consciousness: Speed downstream = 70 + 20 = 90 kmph
Speed upstream = 70 - 20 = 50 kmph
The answer is (D).