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Junior | Next Rank: 30 Posts
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Joined: Tue Jul 08, 2008 1:29 pm

Ratios

by notgoodinmath » Tue Jul 08, 2008 1:49 pm
I am not good at ratios! Can someone explain to me how to answer this question:
A container holding 12 ounces of a solution that is 1 part alcohol to 2 parts water is added to a container holding 8 ounces of a solution that is 1 part alcohol to 3 parts water. What is the ratio of alcohol to water in the resulting solution?
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Junior | Next Rank: 30 Posts
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by Carol » Tue Jul 08, 2008 2:34 pm
lets see if I have it correct...

my approach:

1st: read the question carefully, and since they're asking you for a ratio, don't forget to put it in the right order (check what you're supposed to look for as the nominator and the denominator)

What is the ratio of alcohol to water in the resulting solution?

= alcohol / water -> is the answer 3/7?


resolution:


1st container :

12 ounces: 1 part alcohol to 2 parts water = 3 parts (1+2=3)

if you divide 12 by 3, you'll get the nr of groups that alcohol and water are distributed in, and then find the overall nr of parts.

12/3= 4
4x1 = 4 (in 12 onces, there are 4 parts of alcohol)
4x2=8 (in 12 onces, there are 8 parts of water)

2nd container:


8 ounces: 1 part alcohol to 3 parts water = 4 parts (1+3 =4)

again, if you divide 8 by the nr of parts, you'll know to the nr of parts of alchol and water in 8 ounces.

8/4 =2
2x1=2 (alcohol)
2x3=6 (water)


now that we know the parts in both countainers, we're adding the parts of the countainer 1 to the coutainer 2. and check the raio.

parts of alcohol : 4+2 = 6
parts of water : 8+6 = 14


we're asked for the ratio of alcohol to water : 6/14, which is the same as 3/7

I hope I made everything clear ... :roll:
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Junior | Next Rank: 30 Posts
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Joined: Tue Jul 08, 2008 1:29 pm

by notgoodinmath » Tue Jul 08, 2008 2:40 pm
that was the correct answer! thank you so much! :D
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