Subject :IMO Class : Class 8
With a given rate of simple interest, the ratio of principal and amount for a certain period of time is 4 : 5. After 3 years, with the same rate of interest, the ratio of the principal and amount becomes 5 : 7. The rate of interest per annum is _______.
A4%
B5%
C6%
D7%
Ans 1:
Class : Class 8