A sum of money at simple interest amount to Rs 720 after 2 years and to Rs 1020 after a further period of 5 years.The sum is:	Choose the correct choice from the following:
A) 600	B) 450	C) 650	D) 500	E) 550

Rationale: simple interest for 5 year = rs . ( 1020 - 720 ) = rs . 300 . simple interest for 2 year = rs . ( 300 / 5 × 2 ) = rs . 120 . principal = rs . ( 720 - 120 ) = rs . 600 . answer : a
Answer: A