question:X can finish a work in 20 days. Y can finish the same work in 15 days. Yworked for 9 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 3
(B) 5
(C) 6
(D) 8
(E) 9
answer:(D)
Stream of consciousness:Work done by X in 1 day = 1/20
Work done by Y in 1 day = 1/15
Work done by Y in 9 days = 9/15 = 3/5
Remaining work = 1 3/5 = 2/5
Number of days in which X can finish the remaining work = (2/5) / (1/20) = 8

question:In what time a sum of money double itself at 7% per annum simple interest?
Options:
(A) 33 1/8%
(B) 33 1/3%
(C) 14 2/7%
(D) 33 4/3%
(E) 73 1/3%
answer:(C)
Stream of consciousness:P = (P*7*R)/100
R = 14 2/7%

question:A fair coin is tossed repeatedly. If head appears on the first four tosses, then the probability of appearance of tail on the fifth toss is.
Options:
(A) 1/7
(B) 1/2
(C) 3/7
(D) 2/3
(E) 1/3
answer:
(B)
Stream of consciousness:Since the coin is a fair coin, every toss is independent of any other toss. Hence, the probability of appearance of tail on the fifth toss is = 1/2