The sum of the first 12 terms of an arithmetic progression is 216

MATHEMATICS · Single correct · A Level · Mathematics · Sequences and series · Sequences and series

Problem

The sum of the first 12 terms of an arithmetic progression is 216, while the sum of the first 18 terms is 486. What is its common difference? (a)

4

(b)

1.5

(c)

3

(d)

2.25