Question

A family is evaluating their energy usage. Their current electric hot-water heater raises the water temperature to 140°F, which requires 0.10 kWh/gallon at a cost of $0.10/kWh. Each person in the family of five showers once a day for an average of 10 minutes per shower. The shower has a flow rate of 5.0 gallons per minute. Calculate the annual cost of the electricity for the family showers assuming that 3.0 gallons per minute of the water used is from the hot-water heater.

Answer 1

547.5

Step-by-step explanation:

Answer 2

`C=\$547.5`

Step-by-step explanation:

First, we have to determine the total quantity of hot water spent by the whole family in one year, as follows:

`W=3(gal)/(min)* 10min*5people*365days\\W=54750 gallons`

Then, we calculate the energy required to heat that water:

`E=54750 gall*0.10(kWh)/(gall) \\E=5475 kWh`

Finally, we determine the cost of the energy required by the hot-water heater in one year:

`C=5475 kWh*0.10(\$)/(kWh) \\C=\$547.5`