A train traveling at 72 kmph crosses a platform in 30 seconds and a man standing on the platform in 17 seconds. What is the length of the platform in meters?
Options:
(A) 240 meters
(B) 260 meters
(C) 420 meters
(D) 600 meters
(E) Cannot be determined
Answer and stream of consciousness: (B)
Stream of consciousness: Speed of the train in metres/sec = 72000/3600 = 20
Distance travelled by train to cross the platform = 30 * 20 = 600 = Length of train + Length of platform
Distance travelled by train to cross the man = 17 * 20 = 340 = Length of train
Length of platform = 600 - 340 = 260

Two persons A and B can complete a piece of work in 30 days and 45 days respectively. If they work together, what part of the work will be completed in 3 days?
Options:
(A) 1/8
(B) 1/3
(C) 1/6
(D) 1/2
(E) 5/3
Answer and stream of consciousness: (C)
Stream of consciousness: A's one day's work = 1/30
B's one day's work = 1/45
(A + B)'s one day's work = 1/30 + 1/45 = 1/18
The part of the work completed in 3 days = 3 (1/18) = 1/6.

Calculate the circumference of a circular field whose radius is 8 centimeters.
Options:
(A) 18 cm
(B) 1 cm
(C) 8 cm
(D) 19 cm
(E) 28 cm
Answer and stream of consciousness: (A)
Stream of consciousness: Circumference C is given by
C = 2r = 2*9 = 18 cm

One copy machine can make 30 copies a minute, and a second copy machine makes 15 copies a minute. If the two copiers work together, how long would it take them to make 900 copies?
Options:
(A) 15 minutes
(B) 20 minutes
(C) 25 minutes
(D) 30 minutes
(E) 35 minutes
Answer and stream of consciousness:
(B)
Stream of consciousness: Total work done by both machines in a minute = 30 + 15 = 45 copies
Total number of copies required = 900
Time = 900/45 = 20 mins