Question

If the sum of an arithmetic sequence sequence is 220 and the first term is 10, find the common difference if the last term is 30. ?

Answer 1

`d=2`

Explanation:

`220= n/2(10+30)`

`440=40n`

`n=11`

`30= 10+d(11-1)`

`20=10d`

`d=2`