Question

A1 = 8
ai = ai-1 * 3/4

Find the sum of the first 25 terms of this sequence

Answer 1

31.98 to the nearest hundredth.

Explanation:

This is a geometric sequence with common ratio r = 3/4:

8, 8*3/4, 8*(3/4)^2 ......

Sn = a1 * (1 - r^n) / ( 1 - r)

S25 = 8 * (1 - (3/4)^25) / (1 - 3/4)

= 8 * (0.99925) * 4

= 31.98.