A certain sum is invested at simple interest at 15% p.a. for two years instead of investing at 12% p.a. for the same time period. Therefore the interest received is more by Rs. 900. Find the sum?
Pick
A) s. 7000  B) s. 9000  C) s. 15000  D) s. 17000  E) s. 27000
Let the sum be Rs. x.   (x * 15 * 2)/100 - (x * 12 * 2)/100 = 900   =&gt; 30x/100 - 24x/100 =900   =&gt; 6x/100 = 900   =&gt; x = 15000.   ANSWER:s. 15000
<result>C</result>
A certain sum is invested at simple interest at 15% p.a. for two years instead of investing at 12% p.a. for the same time period. Therefore the interest received is more by Rs. 900. Find the sum?