This problem is equivalent to a Venn diagram. You have a universe of 40 students, within that universe 40% (16) students are taking physics and 30% of the student body (12) students are taking calculus. Now some of those students are taking both courses. In other words they are both in the 40% physics subset, and 30% calculus subset.
We are told that 10% (4) of those students are taking both courses, so we have to add the 16 physics students to the 12 calculus students, giving us a total of 28 students.
Now in essence 4 of those students are an over count since they were in both categories, so we subtract the four from the 28 to get a total of 24 students out of a senior class of 40 taking either or both calculus physics or both.
We now subtract the 24 students from the 40 students and we get 16 students who are taking neither course.
P.S. It is an interesting foot note that their were exactly 16 girls in that class, while that might imply that it was the girls who took neither, it would be an incorrect inference, since we do not have sufficient data to make that claim.
Don't feel bad I am not that great at math either and I took the math problems off a website. I think I can do basic math if I tried but it was never my strong point at all. I was never interested in math.
Either I am reading the question incorrectly or I am just calculating question 7 incorrectly, but I don't see the answer as 16 (which would be 40% of the class!)
I read it as 40% (or 16) are taking Physics, 30% (or 12) are taking Calc, and 10% (4) are taking both.This explanation leaves 8 or 20%.
However another legitimate explanation might conclude that the 10% (those taking both) are already included in those who take Physics or Calc and that there are 30% who take neither in which case the answer is 12 or 30%. Since two got the right answer, I realize I must be missing something simple so an explanation would be appreciated, even though I am embarrassed to ask.
On my page Grandpa it shows that you got a 100%. Maybe you just needed the page to update. Sometimes when I post htings it is kind of slow depending on the traffic.
Math Quiz
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