How to Correctly Express Percentage

[Linda1]

I don't know how to express this: If Nic uses 62425 kwh of electricity and Linda uses 78636, does Linda use 20.6% more? How would this difference be correctly expressed as a percentage? Thanks!

 

[MarkFL]

Hello and welcome to MHB, Linda!

If we let $P$ be the percentage in question, I would write:

$$P=\frac{78636-62425}{62425}\cdot100\%=\frac{64844}{2497}\%\approx25.9688\%$$

 

[HallsofIvy]

The percentage difference is the difference divided by the "base"
Here the difference is 78636- 62425= 16211.

Since this problem said "what percent more", the base is the smaller number, 62425.
$$\frac{16211}{62425}= 0.259$$ or 26%. Linda uses 26% more than Nic.

If the problem had said "What percent less does Nic use than Linda", the base would be the larger number, so we would calculate $$\frac{16211}{78636}= 0.21$$ or 21%. Nic uses 21% less than Linda.