A sum of money amounts to Rs. 9800 after 5 years and Rs. 12015 after 8 years at the same rate of simple interest. The rate of interest per annum is?	Choose one: A) 12.05 % B) 5 % C) 13.05 % D) 22.05 % E) 18.05 %

Rationale: s . i . for 3 years = ( 12015 - 9800 ) = rs . 2215 s . i . for 5 years = rs . 2215 / 3 * 5 = rs . 3691 . principal = ( 9800 - 3675 ) = rs . 6108 hence , rate = ( 100 * 3691 ) / ( 6125 * 5 ) = 12.05 % answer : a
Answer: A