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.

[Q]: Question: The functions f and g are defined for all the positive integers n by the following rule: f(n) is the number of perfect squares less than n and g(n) is the number of primes numbers less than n. If f(x) + g(x) = 16, then x is in the range:

 Option A: 30 < x < 36

 Option B: 30 < x < 37

 Option C: 31 < x < 37

 Option D: 31 < x < 38

 Option E: 32 < x < 38
[A]: Option C


[Q]: Question: On flipping 3 coins together what is the outcomes for at least four tail?

 Option A: 1/7

 Option B: 0

 Option C: 1

 Option D: 4/13

 Option E: 5/13
[A]: Option B


[Q]: Question: Two taps can separately fill a cistern 10 minutes and 18 minutes respectively and when the waste pipe is open, they can together fill it in 18 minutes. The waste pipe can empty the full cistern in?

 Option A: 6

 Option B: 8

 Option C: 1

 Option D: 9

 Option E: 10
[A]:
Option E