the average of 11 numbers is 9.9 . if the average of the first 6 numbers is 10.5 and that of the last 6 numbers is 11.4 , then the middle number is	Choose the correct option
A) 71.5 B) 11.5 C) 81.5 D) 11.5 E) 22.5

Rationale: explanation : middle numbers = [ ( 10.5 x 6 + 11.4 x 6 ) - 9.9 x 11 ] = 22.5 . answer : e
Answer: E