Q: A train 160 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
Options:
(A) 40 sec
(B) 50 sec
(C) 44 sec
(D) 24 sec
(E) 60 sec
A: OK... Stream of consciousness: Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 160 + 140 = 300 m
Required time = 300 * 2/25 = 24 sec
The answer is (D).

Q: A man rows his boat 70 km downstream and 45 km upstream, taking 2 1/2 hours each time. Find the speed of the stream?
Options:
(A) 1 kmph
(B) 6 kmph
(C) 5 kmph
(D) 8 kmph
(E) 7 kmph
A: OK... Stream of consciousness: Speed downstream = d/t = 75/(2 1/2) = 28 kmph
Speed upstream = d/t = 45/(2 1/2) = 18 kmph
The speed of the stream = (28 - 18)/2 = 5 kmph
The answer is (C).

Q: X can finish a work in 36 days. Y can finish the same work in 24 days. Y worked for 12 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 12
(B) 13
(C) 16
(D) 17
(E) 18
A: OK... Stream of consciousness: Work done by X in 1 day = 1/36
Work done by Y in 1 day = 1/24
Work done by Y in 12 days = 12/24 = 1/2
Remaining work = 1 1/2 = 1/2
Number of days in which X can finish the remaining work = (1/2) / (1/36) = 18
The answer is (E).

Q: An analyst will recommend a combination of 3 industrial stocks, 2 transportation stocks, and 2 utility stocks. If the analyst can choose from 5 industrial stocks, 4 transportation stocks, and 4 utility stocks, how many different combinations of 7 stocks are possible?
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Options:
(A) 12
(B) 19
(C) 360
(D) 580
(E) 720
A:
OK... Stream of consciousness: 5C3 * 4C2 * 4C2 = 10*6*6 = 360.
The answer is (C).