Question

Consider a woman puts Php 60000 in an account. After 3 years, she has a total amount of Php 70000. How long will it take to have Php 100000?

Answer 1

$P_i=P(1+ \frac{r}{100})^n$

$70000=60000(1+ \frac{r}{100})^3$

$r=100(\sqrt[3]{70000/60000}-1)=5,27$

$100000=60000(1+\frac{5,27}{100})^n$

$n=log_{1.0527}(100000/60000)=9.946$

Answer: It takes 9.946 year