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: a van takes 5 hours to cover a distance of 495 km. what speed in kph should the van maintain to cover the same distance in 3 / 2 of the previous time ?
Options: a. 60, b. 63, c. 66, d. 69, e. 72

Answer: c


Question: Problem: what sum of money will produce rs. 80 as simple interest in 4 years at 3 1 / 2 percent ?
Options: a. 263, b. 571.4, c. 367, d. 368, e. 339

Answer: b


Question: Problem: the sub - duplicate ratio of 16: 64 is
Options: a. 4: 3, b. 1: 2, c. 1: 3, d. 1: 4, e. 2: 4

Answer:
e