A sum of money amounts to Rs. 9800 after 5 years and Rs. 12005 after 8 years at the same rate of simple interest. The rate of interest per annum is	Choose the correct choice from the following choices:
A) 15 %	B) 12 %	C) 8 %	D) 7 %	E) 5 %

Rationale: "explanation : simple interest for 3 years = ( rs . 12005 - rs . 9800 ) = rs . 2205 simple interest for 5 years = 22053 × 5 = rs . 3675 principal ( p ) = ( rs . 9800 - rs . 3675 ) = rs . 6125 r = 100 × si / pt = 100 × 3675 / 6125 × 5 = 12 % answer : option b"
Answer: B