Insert 8 arithmetic mean between 3 and 21 and find the sum of the series obtained.

Insert three arithmetic mean between 2 and 14.

Determine five arithmetic mean between 3 and 33.

Insert five A.M.'s between 1.2 and 8.4.

Insert five G.M.’s between 3 and 192.

Insert three A.M.'s between 3 1/4 and 1 1/4 .

Insert five G.M.'s between 8 and 1/8 .

The arithmetic mean of 1,2,3…n is

By inserting eight A.M.’s between 2 and 29 prove that the sum of the eight A.M's is equal to eight times of A.M. of 2 and 29.

Find the sum of the first 15 muliples of 8.

Find the arithmetic mean of the following: 3 and 12.