ERLCMath30-2: Confusion in the Textbook (Nelson

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Math 30-2 Staffroom -- A Safe Place to Share and Reflect

Confusion in the Textbook (Nelson - Principles)

I ran into a problem on P. 40 Example 1

when I read the statements "4 children have a dog and a cat" I read this as the intersection of the two sets. However in the solution they have the intersection of those two sets as the expression "4 + x"

Does anyone else get what I'm saying. I thought that the number 4 was an inclusive statement. Why are they then saying that the intersection is '4 + x' ? The same goes for the other two intersections.

Other questions work out fine, but I'm having a real problem with the origional wording in the example.

If I'm off base here, can someone enlighten me?

Thanks!

You miss read the statement. It actually reads "4 children have only a dog and a cat." Since there was also children with birds as pets, the intersection of having all three types of pets was labelled as "x". So a statement "having dog and cat" without the word "only" attached can imply (having a dog and cat and a bird) or (only having a dog and cat). Which would give the x + 4. Hope this helps.

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I set up my venn diagram with the stem information that is given. In my textbook there is not a statement that says "4 children have a dog and a cat only" just "4 children have a dog and a cat" "3 children have a dog and a bird" and "2 children have a cat and a bird" all of these statements are and statements refering to the intersection of the sets.

however I have the pre-publication issue - so maybe they have corrected the wording with the actual textbook.

I just think for the solution method that is shown - those beginning statments need to be only statements.

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I found in the workbook a problem where they mention a statement and assume the four is referring to the "only" spot as I call it with my students. The workbook is mistaken and the textbook does not have this issue that I've run into so far. If they want it to be 4+x, it has to say "ONLY". "And" refers to the intersection of the two.

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I too found a question in the workbook that is problematic. Jeesh! This is frustrating.

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I found my error. I was looking in my pre-publication edition textbook. The wording is correct in the actual textbook that the kids use.

I guess I should throw that textbook out.

Sorry for the confusion that was created for no reason at all :(

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