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.

[EX Q]: Question: The average of first ten prime numbers which are odd is?

 Option A: 15.5

 Option B: 15.7

 Option C: 15.2

 Option D: 15.8

 Option E: 15.1
[EX A]: Option D

[EX Q]: Question: A contractor undertakes to built a walls in 50 days. He employs 60 peoples for the same. However after 25 days he finds that only 40% of the work is complete. How many more man need to be employed to complete the work in time?

 Option A: 25

 Option B: 90

 Option C: 35

 Option D: 20

 Option E: None of these
[EX A]: Option B

[EX Q]: Question: A, B two inlet pipes takes 15,18 minutes to fill the tank and C an oulet pipe takes 45 minutes to empty the tank respectively. In what time the tank be filled if all of them are operated together?

 Option A: 11 minutes

 Option B: 10 minutes

 Option C: 12 minutes

 Option D: 13 minutes

 Option E: 14 minutes
[EX A]:
Option B