Calculate the average of all the numbers between 18 and 57 which are divisible by 7.  Pick one
A) 36.9 B) 38.5 C) 18.5 D) 32.5 E) 28.5

Rationale: "explanation : numbers divisible by 7 are 21,28 , 35,42 , 49,56 , average = ( 21 + 28 + 35 + 42 + 49 + 56 , ) / 6 = 231 / 6 = 38.5 answer : b"
Answer: B