question:A train running at the speed of 60 km/hr crosses a pole in 9 sec. What is the length of the train?
Options:
(A) 350 m
(B) 250 m
(C) 300 m
(D) 148 m
(E) 150 m
answer:(E)
Stream of consciousness:Speed = 60 * 5/18 = 50/3 m/sec
Length of the train = speed * time = 50/3 * 9 = 150 m

question:Ravi can do a piece of work in 30 days while Prakash can do it in 40 days. In how many days will they finish it together?
Options:
(A) 17 1/7 days
(B) 17 1/8 days
(C) 17 5/7 days
(D) 17 3/7 days
(E) 13 1/7 days
answer:(A)
Stream of consciousness:1/30 + 1/40 = 7/120
120/7 = 17 1/7 days

question:If six persons sit in a row, then the probability that three particular persons are always together is?
Options:
(A) 1/9
(B) 1/6
(C) 1/5
(D) 1/2
(E) 1/3
answer:
(C)
Stream of consciousness:Six persons can be arranged in a row in 6! ways. Treat the three persons to sit together as one unit then there four persons and they can be arranged in 4! ways. Again three persons can be arranged among them selves in 3! ways. Favourable outcomes = 3!4! Required probability = 3!4!/6! = 1/5