More Word Problems: If 300 cost $X, how many for 50 cents?

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DC6

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Jun 16, 2008
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Hi All!

If 300 jelly beans cost you X dollars. How many jellybeans can you purchase for 50 cents at the same rate? :?

thanxs
DC6
 
Simple Proportion. Please demonstrate it for us.
 
so would it be:

.5/x = 300
.5=300x
= 150x

That doesn't seem right at all.
 
DC6 said:
so would it be:

.5/x = 300
.5=300x
= 150x
Click to expand...
What is your ratio? You appear to have "half a dollar to x dollars" on the one side of the "equals" sign, but only "300 items" on the other side. Also, shouldn't the "300" correspond to the "x", rather than to the "half"? :oops:

Eliz.
 
DC6 said:
Cost/Jellybeans = x/300 = .5
x = 150
Click to expand...
So your ratio is "cost : number of jellies", with one comparison being "x dollars to 300 jellies", and the other comparison being "half a dollar to one jelly" (the understood "1" not being written)...?

But aren't you supposed to be finding the number of jellies? On what basis are you assuming that each jelly costs fifty cents, and then solving for the cost of three hundred jellies? :shock:

Please reply with a clear listing of your work and reasoning. Thank you! :D

Eliz.
 
Tatoo this on your wrist (under your watch!):
if a = b, then c = b / a * c
 
Denis -

tattoo NOT tatoo. lol :lol:
I can't do math, but Im okay at spelling. Haven't done this kind of math in about 10 years. studying to take the PCAT to go back to school for my PharmD.

Equations are not so intuitive anymore, and as easy as this problem may be. I am at a loss. :oops:
 
DC6 said:
Hi All!

If 300 jelly beans cost you X dollars. How many jellybeans can you purchase for 50 cents at the same rate? :?

thanxs
DC6
Click to expand...
Thinking about UNITS will help you.

300 beans / X dollars ==> Units are beans/dollar.

Don't even consider setting up any ratio, equation or structure with any other unit.

(How Many beans) / 50¢ ==> A little conversion ==> (How many beans) / ½ dollar <== There we have the same units.
 
300 (beans) divided by the cost if them, x is the price of one bean, right? We'll label the price of one bean c. Likewise, "how many" beans (we'll call that y) divided by 50 cents, or half a dollar ($0.50) should also be the price of one bean, c. So knowing that, you can set these two equations, or proportions equal to each other, you can solve for either x or y:

300 / x = c

y / (.50) = c

Set them equal to each other:

300/x = c = y/.50

300 /x = y / (.50)

[(300)*(.50)] / x = y

150 / x = y , where y is the amount of beans you will or can get for 50 cents, or half a dollar.

I think? Hope that helps seeing the steps. Sorry if that's wrong, or I misled/confused you.
 
To add to that, and lessen any confusion: the answer you get (I believe) will have a variable (x) in it, it's not going to be a real integer.
 
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