Answer
a) $\approx 37.3 \ watts$
b) $\approx 6.93 \ decibels$
Work Step by Step
a) We have the formula:
$P=25(e)^{(0.1)d}$
Plug in $d=4$ to obtain:
$P=25(e)^{(0.1)(4)} \approx 37.3 \ watts$
b) We have the formula:
$P=25(e)^{0.1d}$
Plug in $P=50$ to obatin:
$50=25(e)^{0.1 d } \\ 2=(e)^{0.1 d}\\\ln{2}=0.1 d \\d=10\ln{2} \approx 6.93 \ decibels$
