A sum of money lent out at simple interest amounts of Rs.720 after 2 years and to Rs.1020 after a further period of 5 years. Find the principal.

 a) 600
 b) 1740
 c) 120
 d) 6000

SSC CGL-2015

600. Solution Principal + SI for 2 years = Rs. 720 …..(i) Principal + SI for 7 years = Rs. 1020 ….(ii) Subtracting equation (i) from (ii) we get, SI for 5 years = Rs. (1020 -720) = Rs. 300 SI for 2 years = 300× 2/5 = 120 Principal = Rs. 720- Rs. 120 = 600