Answer
7$\%,$ compounded monthly
Work Step by Step
After $t$ years, the balance, $A$, in an account with
principal $P$ and annual interest rate $r$ (in decimal form)
for $n$ compoundings per year: $\displaystyle \quad A=P(1+\frac{r}{n})^{nt}$
for continuous compounding: $\quad A=Pe^{rt}$.
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For $r=$7$\%=0.07,$ compounded monthly (n=12):
$A=14,000(1+\displaystyle \frac{0.07}{12})^{12\cdot 10}\approx 28,135.26$
For $r=$6.85$\%=0.0685$ compounded continuously:
$A=14,000e^{0.0685\cdot 10}\approx 27,772.81$
Return is greater for
7$\%,$ compounded monthly$ .$
