business mathematics

Quantities are said to be in arithmetic progression(A.P) when they increase or decrease by a common difference to get the next or the previous term respectively.

An arithmetic progression be represented by a,
a + d, a+ 2d, ...., a + (n-1)d, where a is the first term; n is the number of terms in the progression and d is the common difference.
In an Arithmetic progression, n'th term = a + (n-1)d

Sum of n terms = (n/2) * [2a + (n-1)d]
If three numbers are in arithmetic progression, the middle number is called the Arithmetic mean.
Arithmetic Mean = (a+b+c)/3 where a,b and c are in Arithmetic Progression

Arithmetic Mean of 'n' terms in Arithmetic progression =
(first term + last term)/2
(or)
1/2{2a + (n-1)d}