Helen Quick made an investment of $$20,542\mathrm{.}75.$ From this investment, she will receive $$2,400$ annually for the next $15$ years starting one year from now.

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What rate of interest will Helen's investment be earning for her? $($Hint: Use Table $4.)($For calculation purposes, use $5$ decimal places as displayed in the factor table provided. Round answer to $0$ decimal places, e$.$g$.25\%.)$

Rate of interest $\%$