Question

Elissa's parents are always telling her to turn off the lights when she leaves a room. A light bulb requires 75 watts to run when it is turned on. The fixture in Elissa's room requires four of these bulbs. Elissa's parents estimate that she leaves the lights on unnecessarily for 2.5 hours per day. How many watt-hours of electricity are used by these bulbs during 2.5 hours?

Answer 1

750 watts-hours are used by four bulbs for 2.5 hours

Explanation:

We know from the information given that:

• One bulb requires 75 watts
• Elissa's room requires four bulbs

To find the watt-hours of electricity that are used by the four bulbs for 2.5 hours you need to:

First, find the watts that the four bulbs require:

`4\cdot 75 \:watts=300 watts`

Next, watts x hours of use = watts hours

`300 \:watts \cdot 2.5 \:hours= 750 \:watt-hours`