Find the sum of all the term in arithmetic progression 180,175,170......25?

1 Answer
Feb 6, 2018

3280

Explanation:

This arithmetic progression has common difference -5

The number of terms is:

(180-25)/5+1 = 32

The average term is the same as the average of the first and last terms, namely:

(180+25)/2 = 205/2

So the sum of the series is:

32 * 205/2 = 16*205 = 3280