Write the formula to find the Arithmetic mean by deviation methodand explain each letter in it?

Find the arithmetic mean of:

Find the arithmetic mean of:

Write the formula for calculating 'Arithmetic mean'. In step deivation method and explain each letter in it.

Write the formulae for the mean in deviation method and also, explain the terms in it.

Derive a formula to find nth arithmetic mean between a and b.

The formula to find mean by step deviation method is