question: Two trains are moving at 50 kmph and 70 kmph in opposite directions. Their lengths are 150 m and 100 m respectively. The time they will take to pass each other completely is?
Options:
(A) 7 1/2 sec
(B) 7 1/7 sec
(C) 7 8/2 sec
(D) 7 1/9 sec
(E) 7 2/2 sec
answer: Stream of consciousness: 70 + 50 = 120 * 5/18 = 100/3 mps
D = 150 + 100 = 250 m
T = 250 * 3/100 = 15/2 = 7 1/2 sec The answer is (D).

q: A pipe can fill a cistern in 20 minutes whereas the cistern when fill can be emptied by a leak in 40 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 17 minutes
(B) 87 minutes
(C) 40 minutes
(D) 27 minutes
(E) 11 minutes
a: Stream of consciousness: 1/20 - 1/40 = 1/40
40 minutes The answer is (C).

question: In a jar there are 3 golf balls and 2 ping pong balls. What is the probability of drawing at least one golf ball when drawing two consecutive balls randomly?
Options:
(A) 1/4
(B) 1/2
(C) 3/5
(D) 9/10
(E) 16/20
answer: Stream of consciousness: P(at least one gold ball) = 1 - P(no golf ball, so 2 ping pong balls) = 1- 2/5*1/4 = 9/10. The answer is (D).

q: A boy runs 200 metres in 36 seconds. What is his speed ?
Options:
(A) 20 km/hr
(B) 24 km/hr
(C) 30 km/hr
(D) 32 km/hr
(E) 34 km/hr
a: Stream of consciousness: 200/36 * 18/5 = 20 km/hr The answer is (A).

question: Which of the following is equal to (y+1)!/y!?
Options:
(A) y-1
(B) 1+(1/y)
(C) 1
(D) y+1
(E) y
answer: Stream of consciousness: (y + 1)! = (y + 1) * x!
(y + 1)!/y! = y + 1 The answer is (D).

question: In an office, 20 percent of the workers have at least 5 years of service, and a total of 16 workers have at least 10 years of service. If 90 percent of the workers have fewer than 10 years of service, how many of the workers have at least 5 but fewer than 10 years of service?
Options:
(A) 32
(B) 64
(C) 50
(D) 144
(E) 160
answer:
Stream of consciousness: (10/100)Workers = 16 = > number of workers = 160
(20/100)*Workers = x+16 = > x = 32 The answer is (A).