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: at what rate percent per annum will a sum of money double in 6 years.
Options: a. 12.5 %, b. 13.5 %, c. 11.5 %, d. 14.5 %, e. 16.6 %

A: e
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Q: Problem: the area of a square field is 625 km 2. how long will it take for a horse to run around at the speed of 25 km / h ?
Options: a. 12 h, b. 10 h, c. 8 h, d. 4 h, e. none of these

A: d
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Q: Problem: the length of a room is 6.5 m and width is 2.75 m. what is the cost of paying the floor by slabs at the rate of rs. 600 per sq. metre.
Options: a. rs. 18725, b. rs. 16725, c. rs. 30725, d. rs. 10725, e. rs. 20725

A:
d
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