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 correct choice.
A) $400 B) $500 C) $600 D) $800 E) $900
Let the sum be $. P.   Then,[P(1+10/100)^2 - P] = 525   -&gt;P[(11/10)^2 - 1] = 525   P = (525*100/21)= 
<gadget id="calculator">(525*100/21)</gadget>
<output>2_500</output>
2500   SUM= $2500   SO SI = $(2500*5*4/100)= 
<gadget id="calculator">(2500*5*4/100)</gadget>
<output>500</output>
$ 500   ANSWER : $500 $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: