How to adjust for an additional variable.

To be clear, I will only accept an answer that uses the numbers provided to answer the question. If you would also like to include the equation in your answer, then please do, but you must also show the solution with the numbers given. I have found that my brain understands concepts better this way.

This is for my own learning, I am not in school.

According to the IIHS, in 2020:

Vermont had 642,495 people and 58 fatal car crashes.

Virginia had 8,632,044 people and 796 fatal car crashes.

We will assume that Vermont had 250,000 cars and Virginia had 2,500,000.

To calculate the number of fatal car crashes per 1,000 people, the equation would be:

(58 / 642,495) x 1000 = Vermont output


(796 / 8,632,044) x 1000 = Virginia output

Now here is my question. If I wanted to adjust for the fact that each state had a different number of cars, how would I do that? I know I will need to adjust the population difference vs number of cars.

My gut instinct tells me it would be something like this:

(58/(250,000 / 642,495)) x 1000 = Vermont output


(796/(2,500,000 / 8,632,044) x 1000 = Virginia output

Edit: or possibly:

((58/250,000) / (58/642,495)) x 1000 = Vermont output


((796/2,500,000) / (58/8,632,044)) x 1000 = Virginia output

What is the proper way to do this?

Thank you in advance!
  • So to be clear, my second guess is correct? Or am I missing something?

    • Mathe Mathe

      The first guess was correct, except for the x1000

  • Can you please write the formula in line format like I did in my question. I want to be sure I understand fully


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Mathe Mathe
The answer is accepted.
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