q: A train 250 m long running at 72 kmph crosses a platform in 20 sec. What is the length of the platform?
Options:
(A) 150m
(B) 200m
(C) 250m
(D) 270m
(E) 300 m
a: Stream of consciousness: D = 72 * 5/18 = 20 = 400 250 = 150m The answer is (A).

question: If 85 percent of the test takers taking an old paper and pencil GMAT exam answered the first question on a given math section correctly, and 70 percent of the test takers answered the second question correctly, and 5 percent of the test takers answered neither question correctly, what percent answered both correctly?
Options:
(A) 60 %
(B) 65 %
(C) 70%
(D) 75%
(E) 80%
answer: Stream of consciousness: {Total} = {First correctly} + {Second correctly} - {Both correctly} + {Neither correctly}
100 = 85 + 70 - {Both correctly} + 5
{Both correctly} = 60. The answer is (A).

q: Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 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) 120 gallons
(D) 180 gallons
(E) 130 gallons
a: 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 = 3 gallonsVolume of whole = 3 * 40 = 120 gallons. The answer is (C).

question: A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 190 m long?
Options:
(A) 40 sec
(B) 42 sec
(C) 44 sec
(D) 48 sec
(E) 50 sec
answer: Stream of consciousness: Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 360 + 190 = 550 m
Required time = 550 * 2/25 = 44 se The answer is (C).

q: The edge of a cube is 6a cm. Find its surface?
Options:
(A) 216a2
(B) 24a4
(C) 24a1
(D) 24a2
(E) 24a7
a: Stream of consciousness: 6a2 = 6 * 6a * 6a = 216a2 The answer is (A).

q: What is the probability that Company Q's advertisement will be one of the first two be shown during the first commercial break?
Options:
(A) 1/ 225
(B) 1 / 30
(C) 1 /15
(D) 2 / 15
(E) 4 /15
a:
Stream of consciousness: Q 1/15 + (14/15) * 1/14 = 2/15 The answer is (D).