Practice Test 2 Question 17

[Perez.Julio79]

Good Morning!

In going over median properties for question 17 the explaination states:

"Since each set has an even number of terms, the median of each set will be equal to the average of the two middle terms of that set."

My question: If I didn't know that principle going into the question, how else would I solve it? I used the average of the four terms for each set and then solved for the expression of variables as such...

...add the four values for Set A and divide by 4 equate that to the sum of the four values of Set B divided by 4 and then solve for (y-x) as in the question.

(3+x+8+10)/4 = (4+y+9+11)/4

my answer is -3 = y-x

Which is wrong, and I don't understand why aside from the previously mentioned senctence which for all intensive purposes should lead to the same answer when one is calculating an average. The correct answer is -1, which does not make sense to me.

I appriciate your time and help with understanding this concept.

Thank you,

Julio

[tommywallach]

Hey Julio,

Hm. You seen to be conflating mean and median. The mean and the median are only equal if it's an evenly-spaced set, which these are not, so you can't use any method that involves the mean.

-t