Question

if a bank account doubles in size every 5 years, then by what percent does it grown after only 3 years ? Round to the nearest tenth of a percent. Hint : First write an expression that would calculate its growth rate after a single year.

Help please !

Answer 1

Answer:

Step-by-step explanation:

Given that a bank account doubles in size every 5 years.

Let P be the principal amount and growth rate = r

Then we have Amount after 1 year = $Pe^{r}$

Similarly after 5 years amount will be

$Pe^{5r}=2P$.

Cancel P to get

$e^{5r}=2$.

Take log to get

5r = ln 2 Or r = 0.1386

=13.86% per annum

to find the percent of growth in 3 years

In three years

$Pe^{3r}$ = 1.516P

Hence growth rate is 1.516 times in 3 years.