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: a goods train runs at the speed of 72 kmph and crosses a 250 m long platform in 24 seconds. what is the length of the goods train ?
Options: a. 230 m, b. 240 m, c. 260 m, d. 270 m, e. none of these
[A]: a


[Q]: Problem: a train covers a distance of 100 km in 1 hour. if its speed is decreased by 15 km / hr, the time taken by the car to cover the same distance will be ?
Options: a. 1 hr, b. 1 hr 10 min, c. 50 min, d. 1 hr 30 min, e. 1 hr 45 min
[A]: b


[Q]: Problem: carolyn bought 17 gumballs, lew bought 12 gumballs, and carey bought x gumballs. the average ( arithmetic mean ) number of gumballs the 3 bought is between 19 and 25, inclusive. what is the difference between the greatest number and the smallest number of gumballs carey could have bought ?
Options: a. 18, b. 20, c. 22, d. 24, e. 26
[A]:
a