Question

A laptop computer consumes about 40 watts of electricity per hour when operating. At $0.20 per kilowatt-hour, how much does a laptop cost to operate for 10 hours?A )8 centsB )800 centsC )40 centsD) 200 cents

Answer 1

A) 8 cents

Step-by-step explanation

Step 1

find the rate

`\begin{gathered} \text{rate}=\text{ 40 }\frac{\text{w}}{h} \\ \end{gathered}`

cost

`\begin{gathered} \text{ Cost= 0.20 per 1000 wats hour} \\ \end{gathered}`

hence

total cost = time*rate*consume

`\begin{gathered} \text{ Total cost = 10 hours}\cdot40(w)/(h)\cdot0.2\frac{\text{ \$}}{1000\text{ w}} \\ \text{ Total cost =}0.08\text{ dollars} \end{gathered}`

now, to convert from dollars to cents, multply by 100

`\text{ Total cost =}0.08\text{ dollars}\cdot(\frac{100\text{ cents}}{1\text{ dollar}})=8\text{ cents}`

I hope this helps you