What is the average of first 21 multiples of 6 ? Options:  A) A)66  B) B)77  C) C)79  D) D)81  E) E)82
Required average = 6(1+2+....+21) / 21   (6/21)X ( (21x22) / 2 ) (because sum of first 21 natural numbers)   = 66   66
<result>A</result>
What is the average of first 21 multiples of 6 ?