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: two taps a and b can fill a cistern in 12 minutes and 18 minutes respectively. they are turned on at the same time. if the tap a is turned off after 4 minutes, how long will tap b take to fill the rest of the cistern ?
Options: a. 8 min., b. 9 min., c. 10 min., d. 7 min., e. none of these
[A]: a


[Q]: Problem: a store sells chairs and tables. if the price of 2 chairs and 1 table is 60 % of the price of 1 chair and 2 tables, and the price of 1 table and 1 chair is $ 64, what is the price, in dollars, of 1 table ? ( assume that every chair has the same price and every table has the same price. )
Options: a. 48, b. 52, c. 54, d. 58, e. 56
[A]: e


[Q]: Problem: a train 300 m long is running with a speed of 68 kmph. in what time will it pass a man who is running at 8 kmph in the same direction in which the train is going ?
Options: a. 6 sec., b. 7 sec., c. 9 sec., d. 18 sec., e. none
[A]:
d