question: Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 6 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?
Options:
(A) 60 gallons
(B) 100 gallons
(C) 240 gallons
(D) 180 gallons
(E) 130 gallons
answer: Stream of consciousness: Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40
Volume of 1/40 part = 6 gallonsVolume of whole = 6 * 40 = 240 gallons. The answer is (C).

q: A train running at the speed of 60 km/hr crosses a pole in 9 seconds. Find the length of the train.
Options:
(A) 150 meter
(B) 250 meter
(C) 200 meter
(D) 480 meter
(E) 153 meter
a: Stream of consciousness: Speed = 60*(5/18) m/sec = 50/3 m/sec
Length of Train (Distance) = Speed * Time
(50/3) * 9 = 150 meter The answer is (A).

question: Find a a prime number the options below.
Options:
(A) 78
(B) 80
(C) 81
(D) 82
(E) 83
answer: Stream of consciousness: Clearly, 83 is a prime number. The answer is (E).

q: The average of 13 numbers is 60. Average of the first 6 of them is 57 and that of the last 8 is 61. Find the 8th number?
Options:
(A) 46
(B) 48
(C) 50
(D) 52
(E) 54
a: Stream of consciousness: Sum of all the 13 numbers = 13 * 60 = 780
Sum of the first 6 of them = 6 * 57 = 342
Sum of the last 8 of them = 8 * 61 = 488
So, the 8th number = 342 + 488 - 780 = 50. The answer is (C).

question: If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 1 strokes ?
Options:
(A) 1/2
(B) 7/8
(C) 1/4
(D) 1/8
(E) 1/16
answer: Stream of consciousness: Left After 1st stroke = 1/2
So removed = 1- 1/2 = 1/2 The answer is (A).

question: X can finish a work in 25 days. Y can finish the same work in 20 days. Y worked for 12 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 2
(B) 5
(C) 6
(D) 7
(E) 8
answer:
Stream of consciousness: Work done by X in 1 day = 1/25
Work done by Y in 1 day = 1/20
Work done by Y in 12 days = 12/20 = 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 The answer is (E).