question: The average of first 12 even numbers is?
Options:
(A) 19
(B) 18
(C) 16
(D) 13
(E) 17
answer: Stream of consciousness: Sum of 12 even numbers = 12 * 13 = 156
Average = 156/12 = 13 The answer is (D).

q: 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 R in the liquid in the tank after 3 minutes?
Options:
(A) 6/18
(B) 6/11
(C) 6/68
(D) 6/19
(E) 6/12
a: Stream of consciousness: Part filled by (A + B + C) in 3 minutes = 3(1/30 + 1/20 + 1/10) = 11/20
Part filled by C in 3 minutes = 3/10
Required ratio = 3/10 * 20/11 = 6/11 The answer is (B).

question: A can do a job in 20 days and B can do it in 30 days. A and B working together will finish twice the amount of work in days?
Options:
(A) 22 1/6
(B) 24
(C) 22 1/0
(D) 22 1/9
(E) 22 1/1
answer: Stream of consciousness: 1/20 + 1/30 = 5/60 = 1/12
12 = 12 *2 = 24 days The answer is (B).

q: The price of a T.V. set worth Rs. 30000 is to be paid in 20 installments of Rs. 1000 each. If the rate of interest be 6% per annum, and the first installment be paid at the time of purchase, then the value of the last installment covering the interest as well will be?
Options:
(A) 22678
(B) 26699
(C) 29000
(D) 19000
(E) 26711
a: Stream of consciousness: Money paid in cash = Rs. 1000
Balance payment = (30000 - 1000) = Rs. 29000 The answer is (C).

question: A man rows his boat 85 km downstream and 45 km upstream, taking 2 1/2 hours each time. Find the speed of the stream?
Options:
(A) 1 kmph
(B) 6 kmph
(C) 5 kmph
(D) 8 kmph
(E) 7 kmph
answer: Stream of consciousness: Speed downstream = d/t = 85/(2 1/2) = 34 kmph
Speed upstream = d/t = 45/(2 1/2) = 18 kmph
The speed of the stream = (34 - 18)/2 = 8 kmph The answer is (D).

question: A can do a piece of work in 3 hours; B and C together can do it in 2 hours, which A and C together can do it in 2 hours. How long will B alone take to do it?
Options:
(A) 6hours
(B) 3hours
(C) 2hours
(D) 5hours
(E) 4hours
answer:
Stream of consciousness: A's 1 hour work = 1/3;
(B + C)'s 1 hour work = 1/2;
(A + C)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/3 + 1/2) = 5/6
B's 1 hour work = (5/6 - 1/2) = 1/3
B alone will take 3 hours to do the work. The answer is (B).