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: 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
[EX A]: b

[EX Q]: Problem: if price of t. v set is reduced by 20 %, then its sale increases by 80 %, find net effect on sale value
Options: a. 44, b. 45, c. 46, d. 47, e. 48
[EX A]: a

[EX Q]: Problem: tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. what is the probability taht the ticket drawn has a number which is a multiple of 3 or 5 ?
Options: a. 1 / 2, b. 2 / 5, c. 8 / 15, d. 9 / 20, e. none
[EX A]:
d