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: michelle deposited a certain sum of money in a savings account on july 1 st, 2007. she earns an 14 % interest compounded semiannually. the sum of money in the account on december 31 st, 2009 is approximately what percent of the initial deposit ?
Options: a. 117 %, b. 120 %, c. 121 %, d. 138 %, e. 145 %

A: d
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Q: Problem: the diagonal of a rectangle is √ 41 cm and its area is 20 sq. cm. the perimeter of the rectangle must be :
Options: ['a. 18', 'b. 28', 'c. 38', 'd. 48', 'e. 58']

A: a
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Q: Problem: there are 2 sections a and b in a class, consisting of 50 and 70 students respectively. if the average weight of section a is 50 kg and that of section b is 70 kg, find the average of the whole class ?
Options: a. 50.78 kg, b. 49.32 kg, c. 61.67 kg, d. 69.15 kg, e. 70.89 kg

A:
c
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