Question

Find the rate of interest per annum on a certain sum of money, if it's interest becomes 4/5th of the sum after 8 years ​

Answer 1

Explanation:

Let principle, p = 100

4 times of p = 400

A=400

SI = A-P

SI = 300

Total SI deviding by rate of interest will get time, and total SI deviding by time will get rate of interest

T = SI/R

T= 300/5 ie : 60 year

T = 60 year

When p become 7 time = A = 700 , R = ?

SI = A-p

SI =700–100= 600

R =SI/T

R= 600/60

R= 10%