Chapter 9 - Section 9.5 - Exponential and Logarithmic Equations - Exercise Set - Page 728: 104

$t=11.22$ years

$P=7250, n=12, r=6.5\%=0.065, A=15000$ $A=P(1+\frac{r}{n})^{nt}=7250(1+\frac{0.065}{12})^{12t}=15000$ $(1+0.00542)^{12t}=2.07$ $12t\log(1.00542)=\log 2.07$ $t=\frac{\log 2.07}{4\log 1.00542}=11.22$ years