Question: Mean of 2 Numbers

Comment on Mean of 2 Numbers

why is this not 40+w since if I make w = 40, I can add 40+40 which will equal 80, and if I divided by 2 the answer will be 40 which is the mean.
greenlight-admin's picture

Hi seny,

We have two numbers. One number is w, and our goal is to find the other number.

If we say that 40+w is the other number, then the two numbers are w and 40+w

What is the average of w and 40+w? Let's find out.

Average = (w + 40+w)/2 = (40 + 2w)/2 = 20 + w

This doesn't work, because question tells us that the average = 40 (not 20 + w)

Now let's perform the test on the actual correct answer (D).

If D is the correct answer then the two numbers are w and 80-w

Average = (w + 80-w)/2 = 80/2 = 40


Does that help?


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