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: an assembly line produces 15 cogs per hour until an initial order of 60 cogs is completed. the speed of the assembly line is then immediately increased so that it can produce 60 cogs per hour until another 60 cogs are produced. what is the overall average output, in cogs per hour, for the assembly line during this whole time ?
Options: a. 20, b. 22, c. 24, d. 26, e. 28

A: c
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Q: Problem: a sum of money at simple interest amounts to rs. 720 after 2 years and to rs. 1020 after a further period of 5 years. the sum is :
Options: a. 400, b. 500, c. 600, d. 700, e. 800

A: c
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Q: Problem: in a village there are 150 men and 90 women in present time. if in next year population will be p = ( a ^ 2 + b ^ 2 ) ^ 1 / 2, and in every year men are reduces 10 %. what is population of after 2 year.
Options: a. 140, b. 141, c. 142, d. 143, e. 144

A:
b
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