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: set s consists of integers { 7, 8, 10, 12, 13 }. if integer n is included in the set, the average ( arithmetic mean ) of set s will increase by 10 %. what is the value of integer n ?
Options: a. 10, b. 12, c. 16, d. 22, e. 24
[EX A]: c

[EX Q]: Problem: the average of first 10 natural numbers is ?
Options: a. 5.6, b. 5.5, c. 5.1, d. 5.8, e. 5.2
[EX A]: b

[EX Q]: Problem: find out the c. i on rs. 5000 at 4 % p. a. compound half - yearly for 1 1 / 2 years ?
Options: a. 272.22, b. 128.29, c. 306.04, d. 198.39, e. 212.22
[EX A]:
c