Question

Natural gas is often priced in units of dollars per therm. One therm equals 100,000 BTUs . A certain family uses 600 therms of energy to heat its home annually using a natural gas furnace that is 80 percent efficient. The family is considering replacing its current furnace with one that is 96 percent efficient. Assuming the cost of a therm is $0.30.
Required:
What would be the family's annual savings in the cost of home heating?

Answer 1

Answer:

-$28.8.

Explanation:

Note, we were told,

• to assume the cost of a therm is $0.30
• the family uses 600 therms of energy annually.

Savings on old furnace:

• 600 * $0.30 * 0.80 (or written as 80%) = $144

Savings on new furnace:

• 600 * $0.30 * 0.96 (or written as 96%) = $172.8

Difference: $144 - $172.8 = -$28.8.