Please help, somebody who is good at math

W

woffer

Temporal Novice
I am trying to figure out this really easy problem and I feel really stupid, can somebody show me how?

Ok, If you have 2/3 of a cup required for 8 servings. How many cups do you need for 30?
This is set up as a proportion like this:

2/3 cup x
---------- = -----------
8 servings 30 servings

If anybody can show me how to do this it would be greatly appreciated.
 
This is not a homework forum, so please do not ask any more questions like that.

But how many (8) servings are there in (30) servings? If it takes 2/3 of a cup for 8 servings and you figured out how many (8) servings there are in (30) servings then you can obtain your own answer to your question.
 
The answer is: 2.5

But as with all things in life, you'll have to pay for the details, if you want them.

2nd Law of Thermodynamics: NO FREE LUNCH
 
woffer,

Let "c" = Cups

Let "S" = Servings

2/3c = 8S

c = 2/3c *1.5

Multiply both sides of the equation by the same factor --> 1.5

(1.5)*2/3c = (1.5)*8 ---> c = 12S

30S/8S = 2.5

Multiply both sides of the equation by the same factor --> 2.5

(2.5)c = (2.5)*8S --> 2.5c = 30S

For 30 servings you need 2.5 cups.
 
that was unneccessarily complicated darby. woffer, to solve a proportion, as the one you set up in your post, multiply the numerator of each side by the denominator of the other. also multiply the quantity labels, and notice how the "servings" label cancels out.

so 2/3 cup * 30 servings = 8 servings * X
20 cup servings = 8 servings * X
2.5 cups = X
 
mmotrh,

Agreed. Your numerical approach was simple, direct and correct. However, when you cancel out "servings" you end up with a unitless value for "X" (a pure number) when you want to end up with "servings" as your result. That's why I avoided that method and took the long route that left servings in the result, i.e. so many cups equals so many servings. Using my solution you can directly say that for any given "c" S = 12c without having to do the algebra again.

But I suppose that for a math, rather than a science, class your method is probably the best method. /ttiforum/images/graemlins/smile.gif
 
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