Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Q: Problem: the dimensions of a room are 25 feet * 15 feet * 12 feet. what is the cost of white washing the four walls of the room at rs. 7 per square feet if there is one door of dimensions 6 feet * 3 feet and three windows of dimensions 4 feet * 3 feet each ?
Options: a. s. 4538, b. s. 6342, c. s. 4518, d. s. 4530, e. s. 4517

A: b
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Q: Problem: if john makes a contribution to a charity fund at school, the average contribution size will increase by 50 % reaching $ 75 per person. if there were 1 other contributions made before john ' s, what is the size of his donation ?
Options: a. $ 100, b. $ 150, c. $ 200, d. $ 250, e. $ 450

A: a
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Q: Problem: 2 + 2 + 2 ² + 2 ³... + 2 ^ 6
Options: a. 2 ^ 9, b. 2 ^ 10, c. 2 ^ 16, d. 2 ^ 35, e. 2 ^ 7

A:
e
****