Question

The sum of 6 consequtive terms of an Arithmetic progression is 90, what is the sum of first and 6th term​

Answer 1

Given:-

The sum of 6 consecutive terms of an Arithmetic progression is 90.

To find:-

The sum of first and 6th term​.

Solution:-

We know,

'a' is the first term and 'l' is the last term of the AP, where 'l' is the 6th term itself.

Number of terms (n) = 6

Sn = n/2 (a+l)

⇒90 = 6/2 (a+l)

⇒90 = 3(a+l)

⇒(a+l) = 90/3

⇒(a+l) = 30

∴The sum of the first and the 6th term​ is 30.