TASK DEFINITION: You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
PROBLEM: Question: A man can do a piece of work in 5 days, but with the help of his son he can do it in 3 days. In what time can the son do it alone ?

 Option A: 13/2

 Option B: 19/2

 Option C: 21/2

 Option D: 15/2

 Option E: None

SOLUTION: Option C

PROBLEM: Question: Pipe A can fill a tank in 16 minutes and pipe B cam empty it in 24 minutes. If both the pipes are opened together after how many minutes should pipe B be closed, so that the tank is filled in 30 minutes?

 Option A: 20

 Option B: 16

 Option C: 24

 Option D: 28

 Option E: 21

SOLUTION: Option E

PROBLEM: Question: A train passes a man standing on the platform. If the train is 160 meters long and its speed is 72 kmph, how much time it took in doing so?

 Option A: 6 Â½ sec

 Option B: 6 Â½ sec

 Option C: 9 Â½ sec

 Option D: 8 sec

 Option E: 7 Â½ sec

SOLUTION:
Option D