An electric clothes dryer uses approximately \(5\) kilowatt-hours of energy to dry a single load of laundry.
On average, Mary Lois’s family washes \(4\) loads of laundry per week. If they use a clothes line instead of the electric dryer to dry half of their loads of laundry, approximately how many kilowatt-hours of energy will they save in a year?
Since half of \(4\) is \(2\), then on average Mary Lois’s family uses the clothes line to dry two loads of laundry per week. This means they would save approximately \(2 \times 5 = 10\) kilowatt-hours of energy each week. Since there are approximately \(52\) weeks in a year, we calculate the total savings as \(52 \times 10 = 520\) kilowatt-hours of energy.