What is the average of first 21 multiples of 5 ?
Choose the correct choice from the following.
A) A)70
B) B)77
C) C)55
D) D)81
E) E)82
Required average = 7(1+2+....+21) / 21   (5/21)X ( (21x22) / 2 ) (because sum of first 21 natural numbers)   = 55   55
<result>C</result>
What is the average of first 21 multiples of 5 ?