Question

The common ratio of a geometric series is 1/4 and the sum of the first 4 terms is 170. what is the first term of the series?

Answer 1

128

Explanation:

The sum of the first n terms of a geometric sequence is:

S = a₁ (1 − r^n) / (1 − r)

170 = a₁ (1 − ¼^4) / (1 − ¼)

a₁ = 128