Given: The difference between compound interest and simple interest on an amount lent for 2 years at the rate of 7% is Rs. 490. Formula Used: Difference between SI and CI for 2 years at rate of interest r is
Pr2
100
C I = Amount – Principal =P(1+
r
100
)n–P SI=
(P×r×t)
100
, Where P is amount, r is rate of interest and t is time period. Calculation: Let the sum be P The difference between compound interest and simple interest on a sum of money lent for 2 years at 7% is 490. ⇒ CI – SI = 490 ⇒ P×{(1+
7
100
)2−1}−
(P×7×2)
100
=490 ⇒ P×[
49
(100×100)
]=490 ⇒ P = 100000 The interest if that amount is again invested for 1 year under compound interest at the rate of 11 % = Rs. (100000×