Question

The Lisbon’s new heat pump cost $4,500.

Answer 1

Answer:

4.1 years.  

Step-by-step explanation:

We have been given that The Lisbon’s new heat pump cost $4,500. They bought it to replace their old furnace and air  conditioner which cost about $2,800 a year to  run. The heat pump will save them approximately  39% a year.

Yearly cost was 2800 at first and the pump will save 39% of 2800. So annual saving with new heat pump will be:

$\frac{39}{100}*2800=0.39*2800$

Let x be the number of years in which heat pump will pay for itself, so saving in x years will be:

$0.39*2800*x$    

Now let us equate the savings by new heat pump with cost of heat pump to find the number of years (x).

$0.39*2800*x=4500$

$1092*x=4500$

$x=\frac{4500}{1092}$

$x=4.1208791208791209\approx 4.1$

Therefore, the heat pump will pay for itself in 4.1 years.

Answer 2

Answer:

4.1 years

Step-by-step explanation: