The average age of 20 students of a class is 20 years. Out of these, the average age of 9 students is 11 years and that of the other 10 students is 24 years. The age of the 20th student is?	Select:  A) 65  B) 61  C) 59  D) 63  E) 64

Rationale: "age of the 20 th student = 20 * 20 - ( 9 * 11 + 10 * 24 ) = 400 - 339 = 61 years answer is b"
Answer: B