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 light flashes every 30 seconds, how many times will it flash in ? of an hour ?
Options: a. 550, b. 600, c. 650, d. 700, e. 120

Answer: e

Question: Problem: the average age of 15 students of a class is 15 years. out of these, the average age of 8 students is 14 years and that of the other 6 students is 16 years, the age of the 15 th student is
Options: a. 17, b. 12, c. 13, d. 14, e. 15

Answer: a

Question: Problem: a man can row a distance of 6 km in 60 min with the help of the tide. the direction of the tide reverses with the same speed. now he travels a further 20 km in 10 hours. how much time he would have saved if the direction of tide has not changed ?
Options: a. 2, b. 8, c. 1, d. 6: 41, e. 5

Answer:
d