How can I determine what the compound interest rate is

[LarryG]

I am trying to determine an interest rate using excel
Example: If I start with $45 and in 5 years it grows to $100, what is the
rate it is compounding at?

 

[David Biddulph]

=((100/45)^(1/5))-1 if the compounding is annually.
Format as percentage if you want to.