Set S consists of integers {6, 7, 10, 12, 15}. If integer n is included in the set, the average (arithmetic mean) of set S will increase by 40%. What is the value of integer n?	Choose the correct choice from the following answers: A) 26 B) 30 C) 34 D) 38 E) 42

Rationale: "the average of the numbers in set s is 10 . if we increase the mean by 40 % , the new mean is 14 . thus , on average , 5 numbers increase by 4 . therefore n = 14 + 20 = 34 the answer is c ."
Answer: C