instruction:
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.
question:
Question: Two pipes A and B can separately fill a cistern in 10 and 15 minutes respectively. A person opens both the pipes together when the cistern should have been was full he finds the waste pipe open. He then closes the waste pipe and in another 4 minutes the cistern was full. In what time can the waste pipe empty the cistern when fill?

 Option A: 7

 Option B: 9

 Option C: 5

 Option D: 4

 Option E: 8
answer:
Option E


question:
Question: In what time will a train 200 m long cross an electric pole, it its speed be 144 km/hr?

 Option A: 2 sec

 Option B: 2.7 sec

 Option C: 3.5 sec

 Option D: 5 sec

 Option E: 9.5 sec
answer:
Option D


question:
Question: If selling price is doubled, the profit triples. Find the profit percent:

 Option A: 200%

 Option B: 500%

 Option C: 100%

 Option D: 450%

 Option E: 800%
answer:

Option C