Answer: The interest rate was 9%.
Step-by-step explanation:
If principal amount P is invested at the rate of r percent with simple interest(I) for t years, the formula to find rate :
[tex]R=\dfrac{I\times100}{P\times t}[/tex]
As per given,
P = $ 500, I = $45, t = 1 year
Substitute values in formula , we get
[tex]R=\dfrac{45\times100}{500\times1}\\\\\Rightarrow R=9\%[/tex]
Hence, The interest rate was 9%.