What is the average of first 21 multiples of 7 ?
Choose the correct answer
A) 49  B) 77  C) 66  D) 57  E) 50
Required average = 7(1+2+....+21) / 21   (7/21)X ( (21x22) / 2 ) (because sum of first 21 natural numbers)   = 77   ANSWER IS 77
<result>B</result>
What is the average of first 21 multiples of 7 ?