x=1.5y OR 1.5x=y???

[brianjadams1]

This question arose while doing #D14 p. 22 OG; however, it is a more general question. The question says "The number of parents who volunteered was 1.5 times the number of parents who neither volunteered to supervise...nor volunteered to bring..." I’m consistently jacking up the setup of problems like these. Is it 1.5Pv=Pn? Or Pv=1.5Pn? I think in this case it’s Pv=1.5Pn, right? But is there a trick to getting the setup in questions like this correct? It’s an on-going problem I’ve had. Thanks!

[junichi]

This question arose while doing #D14 p. 22 OG; however, it is a more general question. The question says "The number of parents who volunteered was 1.5 times the number of parents who neither volunteered to supervise...nor volunteered to bring..." I’m consistently jacking up the setup of problems like these. Is it 1.5Pv=Pn? Or Pv=1.5Pn? I think in this case it’s Pv=1.5Pn, right? But is there a trick to getting the setup in questions like this correct? It’s an on-going problem I’ve had. Thanks!

V = Number of parents who volunteered
N = Number of parents who neither volunteered nor bring

WAS = Equal

V = 1.5N

I used to struggle with opportunity cost, so if you're absolutely stuck, here's what I would do.

The way I read it, it's "For every parent who didn't (blah), there were 1.5 parents who did". So since it's "for every", you can write it as a ratio, and then re-arrange.



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To sum up, I think there's 2 ways you can express relationships. You can say.

X WAS (half/twice/z times) Y
X = (half/twice/z times) Y

or

For every Y, there is (half/twice/z times) of X
(X/Y)=(half/twice/z times)/1

[StaceyKoprince]

Please read (and follow!) the forum guidelines before posting.

This folder is only for general strategy questions, not content or specific test problems. Check out the content / problem folders and post in the relevant folder depending upon the source of the problem you want to post (and make sure to follow the rules about banned sources). If you are a course student, you can also ask about other problems or issues before or after class or during section.

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Quick answer but, if you want to discuss further, please do post in the appropriate folder. :)

Ask yourself which is bigger: The number of carrots is 1.5 times the number of rabbits.

More carrots? Or more rabbits? In this case, more carrots.

I'm going to be setting up a formula that has C = R with a 1.5 in there somewhere. What needs to get multiplied by 1.5 - the larger number or the smaller one?

The smaller one - because multiplying by 1.5 will make it larger, so that it then equals the larger number.

So in this case it's C = 1.5R.

That's the little trick: keep thinking about which one is bigger or smaller, just using your own "common sense" from reading the sentence. :)