Sanjay invested an amount of ` 16,000 for two years on compound interest and received an amount of ` 17,640 on maturity. What is the rate of interest per annum?  Answers
A) 4%	B) 5%	C) 8%	D) 9%	E) None of these
The extra money for two years is 1,640. This can be broken up as 800 + (800 + 40). Since 40 = 5% of 800 and 800 = 5% of 16000   So, r = 5%.   Answer: 5%
<result>B</result>
Sanjay invested an amount of ` 16,000 for two years on compound interest and received an amount of ` 17,640 on maturity. What is the rate of interest per annum?