How many megawatts of windmill generation capacity must be built in order that 25% of the island community's total electricity usage comes from windmills?

Question

One small island community in the pacific currently uses 1.8 megawatts (MW) of electricity per year. All this electricity is generated from plants fired by natural gas. The island community plans to add x MW of offshore windmill generation capacity to its system. How many megawatts of windmill generation capacity must be built in order that 25% of the island community's total electricity usage comes from windmills?

Answer 1

Since x is the increase in MW, the total number of MW would be (x + 1.8).

Also, the MW from windmill is 25% of total usage => x/(x + 1.8) = .25

Solving for x: x = .25(x + 1.8) = .25x + 0.45
.75x = .45
x = 0.6 MW

Answer 2

Since the island currently uses 1.8 MW and wants to generate 25% from wind they will need to generate 25% of 1.8 MW or 1.8MW * .25 which is .45 MW