A sum of money deposited at C.I. amounts to Rs.3250 in 2 years and to Rs.3830 in 3 years. Find the rate percent?  Options:
A) 30 % B) 10 % C) 20 % D) 17 % E) 50 %

Rationale: "3250 - - - 580 100 - - - ? = > 17 % answer : d"
Answer: D