emma puts $10,000 in a simple interest account at a bank. she will earn $1,800 in 4 years. what is the…

emma puts $10,000 in a simple interest account at a bank. she will earn $1,800 in 4 years. what is the annual interest rate for the account?

Answer

4.5

$I = Prt$, where $I$ is interest, $P$ is principal, $r$ is rate, and $t$ is time.

$I = 1800$, $P=10000$, $t = 4$.

$1800=10000\times r\times4$.

First, simplify the right - hand side: $1800 = 40000r$. Then, $r=\frac{1800}{40000}=0.045$.

Multiply by 100: $r = 4.5%$. So the annual interest rate is 4.5.