00:01
The compound interest formula is given to us by a of t is equal to p times 1 plus r over n to the nt.
00:08
And we found in a previous exercise that to isolate the r, we can rewrite this equation so that it is r is equal to n times a to the t, a of t, sorry, over p to the 1 over n times t minus 1.
00:25
So now we want to find the interest rate.
00:30
So we want to find our for an account where the initial investment was $5 ,500.
00:39
So our p is equal to $5 ,500 as that's our initial investment.
00:45
And we know that this account is compound, like interest is compounded monthly, which means that our n is equal to 12, the number of times.
00:55
In one year that interest is compounded, 12 months in a year, therefore it is compounded 12 times.
01:01
And after 30 years, so our t is equal to 30 for the number of years that the money has been in the account, after 30 years, the account now has the value, so a of t is equal to $38 ,000, $38 ,455.
01:21
And we want to find from all of this the interest rate that we were working with.
01:27
So now that i have values for a of t, p, n, and t, i can go ahead and write out this equation that we have up here with the actual values and solve...