q: A pipe can fill a cistern in 20 minutes whereas the cistern when fill can be emptied by a leak in 70 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 17 minutes
(B) 87 minutes
(C) 70 minutes
(D) 28 minutes
(E) 11 minutes
a: Stream of consciousness: 1/20 - 1/70 = 1/28
28 minutes The answer is (D).

question: At 15:00 there were 20 students in the computer lab. At 15:03 and every three minutes after that, 4 students entered the lab. If at 15:10 and every ten minutes after that 8 students left the lab, how many students were in the computer lab at 15:44 ?
Options:
(A) 7
(B) 14
(C) 25
(D) 27
(E) 30
answer: Stream of consciousness: Initial no of students + 3 * (1 + No of possible 3 minute intervals between 15:03 and 15:44) -
8 *(1 + No of possible 10 minute intervals between 15:10 and 15:44)
20 + 3*14 -8 * 4 = 27 The answer is (D).

q: Find the value of y from (12)^3 x 6^4 432 = y?
Options:
(A) 2234
(B) 4350
(C) 4560
(D) 5132
(E) y=5184
a: Stream of consciousness: Given Exp. = (12)3 x 64 = (12)3 x 64 = (12)2 x 62 = (72)2 = 5184
432 12 x 62 The answer is (E).

question: The average of seven numbers is 18. The average of first three numbers is 14 and the average of last three numbers is 19. What is the middle number?
Options:
(A) 27
(B) 29
(C) 31
(D) 34
(E) 35
answer: Stream of consciousness: The total of seven numbers = 7X18 = 126
The total of first 3 and last 3 numbers is = 3 X 14+3 X 19 = 99
So, the middle number is (126 - 99 ) = 27 The answer is (A).

q: In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much?
Look at this series: 88, 3, 80, 12, __, 21 ... What number is missing?
Options:
(A) 72
(B) 78
(C) 68
(D) 30
(E) 70
a: Stream of consciousness: A
72
This is an alternating addition and subtraction series. In the first pattern, 8 is subtracted from each number to arrive at the next. In the second, 9 is added to each number to arrive at the next. The answer is (A).

q: A bullet train 140 m long is running at 60 kmph. In how much time will it pass a platform 410 m long?
Options:
(A) 33 Seconds
(B) 22 Seconds
(C) 41 Seconds
(D) 24 Seconds
(E) 29 Seconds
a:
Stream of consciousness: Distance travelled = 140 + 410m = 550m
Speed = 60 * 5/8 = 50/3m
Time = 550 * 3/50 = 33 Seconds The answer is (A).