## 142. Math Puzzle $3 / 77$

How long can a $60 \mathrm{~W}$ light bulb burn until $1 \mathrm{kWh}$ is consumed? What are the energy costs?
A 60 W incandescent lamp can burn for $x$ hours, where $60 \cdot x=1000 \mathrm{Wh}$; $x=16.67 \mathrm{~h}=16 \mathrm{~h} 40 \mathrm{~min}$. The cost of $1 \mathrm{kWh}$ of household energy in our state is only 8 pennies!