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Work Shown:
Use the compound interest formula
A = P*(1+r/n)^(n*t)
A = 10000(1+0.039/1)^(1*4)
A = 11,653.65589441
A = 11,653.66
That's the amount of money Tammy will have at the end of 4 years.
Subtract off the principal from this value to get the interest.
interest = A - P
interest = 11,653.66 - 10,000
interest = 1,653.66