At what rate of compound interest per annum will a sum of Rs. 1200 become Rs. 1348.32 in 2 years?  Choose the correct option:
A) 6 % B) 6.5 % C) 7 % D) 7.5 % E) 8 %

Rationale: explanation : let the rate be r % p . a . then , 1200 x ( 1 + r / 100 ) 2 = 1348.32 = ( 1 + r / 100 ) 2 = 134832 / 120000 = 11236 / 10000 ( 1 + r / 100 ) 2 = ( 106 / 100 ) 2 = > 1 + r / 100 = 106 / 100 r = 6 % answer is a
Answer: A