Chapter 3 - Review Exercises - Page 513: 66

$ x\approx 3.85$

$10^{x}=7000$ We can't show the RHS as a power of 10, so we apply $\log($...$)$ to both sides $\log 10^{x}=\log 7000\qquad $ ... apply basic property, $\log_{b}b^{x}=x $ $ x=\log 7000\qquad $ ... use a calculator and round to two decimal places $ x\approx 3.85$