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: There are six cards in which it has two king cards. all cards are turned down and two cards are opened what is the possibility to get two kings.

 Option A: 1/15

 Option B: 2/15

 Option C: 3/15

 Option D: 4/15

 Option E: 6/15
answer:
Option A


question:
Question: Two numbers are in the ratio 3:5. If 9 be subtracted from each, they are in the ratio of 9:17. The first number is?

 Option A: 36

 Option B: 67

 Option C: 87

 Option D: 56

 Option E: 51
answer:

Option A