What is the average of the squares of the counting numbers from 1 to 7?
A21
B20
C22
D25
Answer:
B. 20
Read Explanation:
The average of the squares of the counting numbers from 1 to n is given by
= (n+1)(2n+1)/6
The average of the squares of the counting numbers from 1 to 7 is
= (7 +1)(2×7 + 1)/6
= 8 × 15/6
= 20
