Find the average of all the numbers between 11 and 34 which are divisible by 5?  Choose the correct choice
A) 10
B) 20
C) 22
D) 30
E) 15

Rationale: "average = ( 15 + 20 + 25 + 30 ) 4 = 90 / 4 = 22 answer is c"
Answer: C