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

Find the arithmetic mean of the following: 7 and 29.

Find the arithmetic mean of the following: -6 and -30 .

Find the arithmetic mean of the following: (x-a)^2 and (x+a)^2 .

Find the mean of the following data:

Find the mean of the following data:

The arithmetic mean of 1,2,3…n is

Find the mean of the following distribution.

The perimeter of /_\ABC is 6 times the arithmetic mean of the sines of its angles. If a = 1, find the angle A