Chapter 9 - Section 9.8 - Exponential and Logarithmic Equations and Problem Solving - Exercise Set - Page 591: 45

9.92 years

We are asked to find how long it would take 600 dollars to double at 7 percent interest, compounded monthly. We get: $A=P(1+(.07/12))^{12t}$ We know that A/P is 2, so: $2 = (1+(.07/12))^{12t}$ $12t= log_{(1+(.07/12))}(2)$ 9.92 years