Chapter 22, Problem 93A

To determine

Time of stereo play.

Answer to Problem 93A

  $t=166.67\text{hours}$

Explanation of Solution

Given:

Total money that a person has, $\text{cost}=\$5$

Power of stereo, $P=200\text{W}=0.2\text{kW}$

Electricity rate $\$0.15/\text{kWh}$

Formula Used:

The energy is given as,

  $E=Pt=\frac{\text{cost}}{\text{rate}}$

Where, $P$ is power in kW, $t$ is time in hour, rate is in per kWh and cost is the total charge of electricity.

Calculation:

On substituting the values in above relation

  $\begin{array}{c}\left(0.2\right)\times t=\frac{5}{0.15}\\ t=\frac{5}{0.15\times 0.2}\\ =166.67\text{hours}\end{array}$

Conclusion:

Therefore, the person can play the stereo for $t=166.67\text{hours}$ .