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.
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Question: Problem: the average weight of a group of persons increased from 48 kg to 51 kg, when two persons weighing 78 kg and 93 kg join the group. find the initial number of members in the group ?
Options: a. 87, b. 67, c. 23, d. 75, e. 25

Answer: c


Question: Problem: a store reported total sales of $ 460 million for february of this year. if the total sales for the same month last year was $ 320 million, approximately what was the percent increase in sales ?
Options: a. 2 %, b. 17 %, c. 44 %, d. 65 %, e. 83 %

Answer: c


Question: Problem: two pipes can fill a tank in 18 minutes and 6 minutes. an outlet pipe can empty the tank in 45 minutes. if all the pipes are opened when the tank is empty, then how many minutes will it take to fill the tank ?
Options: a. 1 / 15, b. 1 / 6, c. 1 / 11, d. 1 / 10, e. 1 / 12

Answer:
b