Chapter 12 - Exponential Functions and Logarithmic Functions - 12.4 Properties of Logarithmic Functions - 12.4 Exercise Set - Page 810: 59

$1.953$

Using the properties of logarithms, the given expression, $ \log_b 15 ,$ is equivalent to \begin{array}{l}\require{cancel} \log_b (3\cdot5) \\\\= \log_b 3+\log_b 5 .\end{array} Since it is given that $ \log_b 3=0.792 $ and $ \log_b5=1.161 $, the expression above, $ \log_b 3+\log_b 5 ,$ evaluates to \begin{array}{l}\require{cancel} 0.792+1.161 \\\\= 1.953 .\end{array}