How many terms are there in the G.P. 5, 10, 20, 40,... 1280?
(a) 6
(b) 8
(c) 9
(d) 10
Correct option (c) 9
Explanation:
1280 = 5. 2n−1 or n − 1 = 8 or n = 9. Thus, there are total of 9 terms in the series.