Explanation

GP series = 4, 8, 16, 32, ... 512.

FORMULA USED:

Tn = ar(n-1)

SOLUTION:

GP series = 4, 8, 16, 32, ... 512.

Tn = ar(n-1)

⇒ 512 = 4 × 2(n - 1)

⇒ 128 = 2(n - 1)

⇒ 27 = 2(n - 1)

Now comparing powers we obtain;

⇒ n - 1 = 7

⇒ n = 8