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: Which of the following CANNOT be weighed using a balance scale and these unit weights: 1, 4, 7, and 10

 Option A: 13

 Option B: 15

 Option C: 17

 Option D: 19

 Option E: 21

SOLUTION: Option A

PROBLEM: Question: A cistern can be filled by a tap in 3 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?

 Option A: 2.9 hrs

 Option B: 4.5 hrs

 Option C: 2.9 hrs

 Option D: 7.2 hrs

 Option E: 8.6 hrs

SOLUTION: Option B

PROBLEM: Question: If the ratio of boys to girls in a class is B and the ratio of girls to boys is G; then 5 (B + G) is ?

 Option A: Equal to 3

 Option B: Less than 5

 Option C: More than 5

 Option D: Less than 1/5

 Option E: none of these

SOLUTION:
Option A