question:In what time will a railway train 20 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 5 sec
(B) 4 sec
(C) 3 sec
(D) 6 sec
(E) 2 sec
answer:(E)
Stream of consciousness:T = 20/36 * 18/5 = 2 sec

question:A man purchases 8 pens for Rs.9 and sells 9 pens for Rs.8, how much profit or loss does he make?
Options:
(A) 15
(B) 66
(C) 88
(D) 1
(E) 12
answer:(A)
Stream of consciousness:90 * 10/60 = 15 kmph

question:A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?
Options:
(A) 12 days
(B) 15 days
(C) 18 days
(D) 20 days
(E) 22 days
answer:
(C)
Stream of consciousness:A's two day's work = 2/20 = 1/10
(A + B + C)'s one day's work = 1/20 + 1/30 + 1/60 = 6/60 = 1/10
Work done in 3 days = (1/10 + 1/10) = 1/5
Now, 1/5 work is done in 3 days
Therefore, Whole work will be done in (3 x 5) = 15 days.