A professor wants to supplement her pension with investment interest. If she invests $26,000 at 7% interest, how much more would she have to invest at 9% to achieve a goal of $4,160 per year in supplemental income?

Answer 1

What is the interest period? Annually, quarterly, monthly, or what?

Assuming annually. Make adjustments if otherwise.

Supplemental income is interest earned over the period. For one year this is:

4160 = 0.07*26000 + 0.09*x

Solve for x.