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.

[EX Q]: Problem: a train traveling at 72 kmph crosses a platform in 33 seconds and a man standing on the platform in 18 seconds. what is the length of the platform in meters ?
Options: a. 240 meters, b. 360 meters, c. 420 meters, d. 300 meters, e. can not be determined
[EX A]: d

[EX Q]: Problem: the average score of a cricketer in 2 matches is 30 and in other 3 matches is 40. then find the average score in all the 5 matches ?
Options: a. 25, b. 27, c. 30, d. 35, e. 36
[EX A]: e

[EX Q]: Problem: dhoni bought 5 toys with the average cost of $ 10. if david also buys the sixth toy with the price of $ 16, what is the average ( arithmetic mean ) price of those 6 toys ?
Options: a. $ 10, b. $ 7, c. $ 8.5, d. $ 9, e. $ 11
[EX A]:
e