Compound interest

Question

Compound interest; find the number of years
Equation given: A = P(1+R/100)x

A= amount of money accruing after x years
P= principal amount
R= rate % per annum
x= number of years for which the money is invested

Question: $500 invested or x years at 11% per annum becomes $842.50. Hence x is?

Answer 1

842.50 = 500(1 + 0.11)^x

1.685 = 1.11^x

ln 1.685 = x ln 1.11

0.521765563 ≈ 0.10436x

4.999669 ≈ x

 

Let's say it takes 5 years.