A sum of money lent out at simple interest amounts to Rs720 after 2 years and to Rs1020 after a further period of 5 years The sum is?
Given, Amount=A1 =Rs 720Time = 2 yrsLet P=Principaland R=Rate %Simple Interest after 2 yrs = A1- PNow,720-P=(P x R x 2)/ 100=(P x R x 2)/100 ................(I)Next, Amount = A2 = Rs 1020Time = 2 + 5 =7 yrs (i.e 2 + a further period of 5 yrs)R= Rate %( same as above)Simple Interest after 7yrs = A2- Pnow,1020-P =( P x R x 7)/100 ..................(II)Next,equation (I) divided by equation (II), we get7 (720-P) = 2(1020-P)solving it we get 5P=3000or, P = Rs. 600.Ans.if you want to get the value of R, substitute the value of P in either of the equation then you'll get it to be 10%.( This problem was solved by Shri. Junemon Paswet from Ladthadlaboh Jowai,West Jaintia Hills District. on the 23/0ct/2012 )