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: if a - b = 6 and a 2 + b 2 = 50, find the value of ab.
Options: a. a. 7, b. b. 12, c. c. 15, d. d. 18, e. e. 20

Answer: a


Question: Problem: the present population of a town is 2000. population increase rate is 20 % p. a. find the population of town after 1 years ?
Options: a. 1000, b. 2400, c. 1500, d. 1600, e. 1250

Answer: b


Question: Problem: a metallic sphere of radius 24 cm is melted and drawn into a wire, whose radius of cross section is 16 cm. what is the length of the wire ?
Options: a. 26 cm, b. 45 cm, c. 58 cm, d. 63 cm, e. 72 cm

Answer:
e