Answer:
7.04 h
Explanation:
First, we determine the power required to heat the wall solving the Fourier's Law equation as follows:
Thermal conductivity of concrete:
[tex]k=2.5\frac{J}{smK}[/tex]
[tex]\frac{Q}{\Delta t} =-kA\frac{\Delta T}{\Delta x}\\\frac{Q}{\Delta t} =-2.5\frac{J}{smK}\times8.8m^2\frac{12.0^\circ C-19.1^\circ C}{0.11m}\\\frac{Q}{\Delta t} =1420 \frac{J}{s}=1.42 kW\\\\C=0.10 \frac{\$}{kWh}\times1.42kWh= \$0.142\\\\h=\frac{\$1}{0.142}= 7.04 h[/tex]
Finally,we determine the cost of the energy required to heat the wall per hour. Then, to determine the hours of power equivalent to $1, we divide and get the number of hours.
