why divide instead of multiplying. Power

Question

I have a 50kw avearage power consumption per month for the year and I have an efficiency of .72 the problem says I need to divide the 50Kw by .72. My question is why divide by .72 and not multiply by .28. 100-72=28 .28 lost of power due to  inefficiencies  the goal is to make up for the energy loss. 

Answer 1

Let's look at what happens if you do it incorrectly.  50kW (0.28) = 14kW so you try upping your production to 64kW x 0.72 = 46.08kW which is not enough.  You have actually fallen short by 14kW x 0.72.  The extra 14kW are subject to the same efficiency of 0.72.

 

 

You are looking for (x kW )(0.72) = 50kW 

x kW = 50kW/(0.72)