Mathematics

Problem

Let

2^{\text{nd}}

8^{\text{th}}

and

44^{\text{th}}

terms of a non-constant A. P. be respectively the

1^{\text{st}}

2^{\text{nd}}

and

3^{\text{rd}}

terms of a G. P. If the first term of the A. P. is 1, then the sum of its first 20 terms is equal to (a) 990 (b) 980 (c) 970 (d) 960