Roberta deposited 4,790.23 into a saving account with an interest rate of 3.8% compunded twice a year. about how long will it takefor the account to be worth 9,000?

4009 is the answer I got

The answer to this question would be: 17 years

The interest rate is 3.8% compounded twice a year. The function of the saving account amount would be:

f (x) = 4,790.23 * (1 + 0.038/2) ^2x

f (x) = 4,790.23 * (1.019) ^2x

Then for f (x) = 9,000 the x value would be:

9,000 = 4,790.23 * (1.019) ^2x

9,000/4,790.23 = (1.019) ^2x

1.8788 = (1.019) ^2x

2x=34

x=17