The difference between compound interest and simple interest on a certain amount of money at 5% per annum for 2 years is 18. Find the sum : Pick one:
A) 4500
B) 7500
C) 5000
D) 7200
E) None of these
Sol.(d) Let the sum be 100.   Therefore, SI = 100×5×2100=10100×5×2100=10   and CI = 100(1+5100)2−100100(1+5100)2−100   ∴ =100×21×2120×20−100=414=100×21×2120×20−100=414   7200ifference of CI and SI = 41⁄4 - 10 = 1⁄4   If the difference is 1⁄4 , the sum = 100   =&gt; If the difference is 18, the sum   = 400 × 18 = 7200 Answer 7200
<result>D</result>
The difference between compound interest and simple interest on a certain amount of money at 5% per annum for 2 years is 18. Find the sum :