Answer
a. 28A
b. $8.4\times10^{4}C$
Work Step by Step
a. Use equation 18–2, which defines the resistance.
$$I=\frac{V}{R}=\frac{240V}{8.6\Omega}=28A$$
b. Use the definition of current, equation 18–1.
$$I=\frac{\Delta Q}{\Delta t}$$
$$\Delta Q=I\Delta t=(27.91A)(50min)( 60s/min)=8.4\times10^{4}C$$