In following number series, two terms have been put within brackets. Choose the appropriate option - In the series 7, 14, 28, ..., what will be the 10th term ?
Answer: C. 3584
Clearly, 7 x 2 = 14, 14 x 2 = 28, ... so on. So, the given series in a G.P. in which a = 7 and r = 2. .'. 10th term = ar(10 - 1) = ar9 = 7 x 29 = 7 x 512 = 3584. Hence the answer is (c).