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 ratio of a to b to c is 2 to 3 to 4, and a, b, c are positive integers. If the average (arithmetic mean) of the three numbers is 36, what is the value of a?

 Option A: 21

 Option B: 24

 Option C: 25

 Option D: 27

 Option E: 30

A: Option B
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Q: Question: Find the average of all the numbers between 11 and 36 which are divisible by 5

 Option A: 15

 Option B: 20

 Option C: 25

 Option D: 30

 Option E: 35

A: Option C
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Q: Question: Robert purchased $4000 worth of US saving bonds. If bonds are sold in $50 or $100 denominations only, which of the following CANNOT be the number of US saving bonds that Robert purchased?

 Option A: 20

 Option B: 47

 Option C: 50

 Option D: 80

 Option E: 90

A:
Option E
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