Question

if interest on 1800 is 500 for 4 years rate of interest is what​

Answer 1

In how many years will the interest on Rs. 1800 at 3% rate of interest be equal to the interest on Rs. 1080 for 4 years at 5% rate of interest?

Consider Simple Interest :

Interest on Rs. 1080 for 4 years at 5% = 1080 * 0.05 * 4 = Rs. 216

Let the no. of years = t for the first case ( Principle Rs. 1800, rate 3%)

So, we have 1800 * 0.03 * t = 216

Or, t = 216/(1800 * 0.03 ) = 4 years Ans.

Consider Compound interest :

Interest on Rs. 1080 for 4 years at 5% = 1080 * ( 1 + 5/100)^4 - 1080 = Rs.232.75

Let the no. of years = t for the first case ( Principle Rs. 1800, rate 3%)

So, we have 1800 * ( 1 + 3/100)^t - 1800 = 232.75

Or, 1.03^t = (232.75+1800)/1800 = 1.1293

Taking logarithm on both sides, t * log 1.03 = log 1.1293

Or t = log 1.1293/log 1.03 = 4.114 years Ans