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: the sum of the ages of 5 children born at the intervals of 3 year each is 60 year. what is the age of the youngest child ?
Options: a. 4 year, b. 6 year, c. 10 year, d. none of these, e. 9 year
[A]: b


[Q]: Problem: the average runs scored by a batsman in 30 matches is 50. in the next 15 matches the batsman scored an average of 26 runs. find his average in all the 45 matches ?
Options: a. 31, b. 42, c. 29, d. 97, e. 27
[A]: b


[Q]: Problem: excluding stoppages, the speed of a bus is 58 kmph and including stoppages, it is 40 kmph. for how many minutes does the bus stop per hour ?
Options: a. 19, b. 19.13, c. 10.5, d. 11.35, e. none of these
[A]:
a