This is a question of compound interest. Compound interest is interest on a principal amount, as well as any accumulated interest from previous periods. To solve for the interest rate, we can use the formula:
A = P(1 + r/n)^(nt)
Where:
A = final amount
P = principal amount
r = interest rate (as a decimal)
n = number of times the interest is compounded per year
t = number of years the money is invested
We can set up the equation to solve for r:
5700 = 3900(1 + r/12)^(12*10)
and then use a calculator or a spreadsheet software to solve it.
The interest rate, to the nearest tenth of a percent, is 9.9%.