Question

A 60-watt light bulb uses 60 watt hours of electricity in 1 hour. Suppose everyone in the United States lef one unneeded 60 watt light bulb on for one hour everyday for a year.

Electricity is billed in kilowatt hours. So 60 watt hours is equal to sixty divided by one thousand. Express the electricity used by a 60 watt light bulb in one hour in kilowatt hours in scientific notation.

Answer 1

`2.19 * 10^(1)` kilowatt-hours.

Explanation:

If a 60-watt light bulb is used every day for one year, then this will consume (365 × 60) = 21900 watt-hours of electricity.

{Because one complete year consists of 365 days}

This 21900 watt-hour is equivalent to
`(21900)/(1000) = 21.9` kilowatt-hours.

Therefore, in scientific notation the electricity consumed by each bulb in kilowatt-hour is
`2.19 * 10^(1)`. (Answer)