Question

Find the number of terms in the GP :2, 4, 8, ...., 2048

• A. 11
• B. 10
• C. 12
• D. 13

Answer 1

Answer:

A. 11

$a=2, r=4/2=2, a_n=2048$

$a_n=ar^{(n-1)}$

$2048=2\times2^{(n-1)}$

$2048/2=1024=2^{(n-1)}$

$2^{10}=2^{(n-1)}$

$n-1=10$

$n=10+1=11$