Question

Zahra is anxious to save money on her utility bills and knows that changing the temperature of the water when she does laundry can help save money. Right now three-fourths of all her laundry is done with the hotter water. Use the table below to determine how much she currently pays in utility costs for laundry. Assume 1 load of wash per day.

Clothes washer w/electric water heater
Cost per load
Hot wash & warm rinse
71 cents per load
Warm wash & cold rinse
25 cents per load

If she cuts down the amount of laundry that she does in hot water to one-half, about how much will she save every year?
a.
$65 each year
b.
$42 each year
c.
$23 each year
d.
$392 each yea

Answer 1

Current average cost per load = 0.75(0.71) + 0.25(0.25) = $0.595 → annual cost = 365 × 0.595 = $217.18.

If hot water is half the loads: average cost = 0.5(0.71) + 0.5(0.25) = $0.48 → annual cost = 365 × 0.48 = $175.20.

Savings ≈ $217.18 − $175.20 = $41.98 ≈ $42. Answer: b.