In an arithmetic progression the first term is and the th term is

MATHEMATICS · Single correct · CBSE · Mathematics · Arithmetic Progressions · Arithmetic Progressions

Problem

In an arithmetic progression the first term is

10

and the

n

th term is

70

. If the sum of the first

n

terms is

400

, then

n

equals (a)

11

(b)

10

(c)

8

(d)

4