A sum of money deposited at C.I. amounts to Rs.1820 in 4 years and to Rs.2402 in 5 years. Find the rate percent?
Choose the correct choice from the following.
A) 30 %  B) 31 %  C) 34 %  D) 19 %  E) 50 %

Rationale: "1820 - - - 582 100 - - - ? = > 31 % answer : b"
Answer: B