The compound interest on a certain sum for 2 years at 10% per annum is $525. The simple interest on the same sum for double the time at half the rate percent per annum is:  Choose the most appropriate option.
A) 400  B) 500  C) 600  D) 800  E) 1000
Let the sum be $. P.   (P(1+10/100)^2-P)=525   P((11/10)^2-1)=2500   SUM = 2500   So SI = 500   ANSWER 500
<result>B</result>
The compound interest on a certain sum for 2 years at 10% per annum is $525. The simple interest on the same sum for double the time at half the rate percent per annum is: