Question

How many terms of the G.P. 1, 4, 16, 64, ........ will make the sum 5461?

Options

• 6

• 9

• 7

• 8

Answer 1

7

Explanation: 

The sum of $$n$$ terms is $$\frac{4^n - 1}{3}$$. Setting this equal to $$5461$$ gives $$4^n = 16384 = 4^7$$, hence $$n = 7$$.