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: Rahim bought 4 pillows with the average cost of $5. If Rahim also buys the fifth pillow with the price of $ 10, what is the average (arithmetic mean) price of those 5 pillows?

 Option A: $6

 Option B: $5

 Option C: $5.5

 Option D: $6.5

 Option E: $7

A: Option A
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Q: Question: How many words can be formed by taking 4 letters at a time out of the letters of the word MATHEMATICS.

 Option A: 2154

 Option B: 2454.

 Option C: 2254

 Option D: 2354

 Option E: 1245

A: Option B
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Q: Question: After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. What is the difference between the ages of the replaced and the new member ?

 Option A: 10

 Option B: 11

 Option C: 22

 Option D: 15

 Option E: 18

A:
Option D
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