instruction:
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.
question:
Problem: the difference between the compound interest compounded annually and simple interest for 2 years at 20 % per annum is rs. 216. find the principal ?
Options: a. 2277, b. 2667, c. 5400, d. 2766, e. 1811
answer:
c

question:
Problem: there is one 4 - digit whole number n, such that the last 4 digits of n 2 are in fact the original number n
Options: a. 8476, b. 7376, c. 9376, d. 7378, e. 9466
answer:
c

question:
Problem: jack and jill are marathon runners. jack can finish a marathon ( 42 km ) in 7 hours and jill can run a marathon in 4.2 hours. what is the ratio of their average running speed ? ( jack: jill )
Options: a. 14 / 15, b. 15 / 14, c. 5 / 5, d. 5 / 4, e. can not be determined
answer:
c