Question

last year, wind turbines along a hilly ridge had an average output of 390 kilowatt hours per year. the turbines were upgraded, and now their average annual output is 90% more. what is the new average yearly output?

kilowatt hours

Explanation:

Step1: Find the increase amount

The increase is 90% of the original output. So we calculate 90% of 390. First, convert 90% to decimal, which is 0.9. Then the increase amount is $390\times0.9 = 351$.

Step2: Calculate the new output

The new output is the original output plus the increase. So we add 390 and 351. $390 + 351 = 741$. (Alternatively, we can use the formula for percentage increase directly: new output = original output×(1 + percentage increase in decimal). So $390\times(1 + 0.9)=390\times1.9 = 741$.)

Answer:

741