quote:

Originally posted by Search&Rescue in every number you have in parentheses, you have assumed the original mass of the alloy to be either 100% copper (when you're calculating the mass of the copper in each) or 0% copper (when you're calculating the mass of contituents other than copper in each)

I don't think he is...

He's saying that 60% of the 204g is copper...122.4g...etc

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Originally posted by chinamon chinamon is INCH MOAN. LOL so fitting.

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Originally posted by Search&Rescue ..and that's just one way of solving linear equations

And can you please tell me where mine was wrong?????

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Originally posted by chinamon chinamon is INCH MOAN. LOL so fitting.

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Originally posted by VDub I don't think he is... He's saying that 60% of the 204g is copper...122.4g...etc

his formula is correct....I just can't figure out the long form of how to do it right now.

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Scott has been introduced to the rave scene, and Ecstasy, by Craig. The two of them go out on the weekends, with some of Craigs friends, and stay up all night, dancing in a drug-fueled trance.

Last edited by Moral Hazard on Apr-26-2011 at 07:48

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Originally posted by ChemEnhanced his formula is correct....I just can't figure out the long form of how to do it right now.

Yah I agree it's correct....

I just can't see where I screwed up...

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quote:

Originally posted by chinamon chinamon is INCH MOAN. LOL so fitting.

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Originally posted by ChemEnhanced yeah...I get to .6(400-y) + y = 204 without a problem...but this is where I get lost solving for y. I am just forgeting the rules....like I said...its been way too long.

try this then since its a little less tedious:

1) x + y = 400
2) 0.60x + 0.40y = 204

multiple 1) by 0.60 (each term on the left and right hand side)
you get:
1) 0.60x + 0.60y = 400 x 0.6

now subtract 1) from 2). you get:
0.20y = (400 x 0.6) - 204
divide both sides by 0.20 to get your final value for y

Last edited by Search&Rescue on Sep-29-2008 at 23:42

quote:

Originally posted by VDub I don't think he is... He's saying that 60% of the 204g is copper...122.4g...etc

that's the problem.
you have to take 60% of the total mass of the alloy which is not 204g. That's really the unknown - what you're trying to find

204g is the sum of the copper content in BOTH alloys

You guys were screwing up because you calculating the %60/%40 from the 204g.......when the question was asking about the ORIGINAL pieces, not the final piece.

Read the question again, and then look at your calculations. You should not be basing it on the final 204g........

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quote:

Originally posted by cammaxwell You guys were screwing up because you calculating the %60/%40 from the 204g.......when the question was asking about the ORIGINAL pieces, not the final piece. Read the question again, and then look at your calculations. You should not be basing it on the final 204g........

I got it figured out now....I was making things more difficult then they needed to be.

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quote:

Scott has been introduced to the rave scene, and Ecstasy, by Craig. The two of them go out on the weekends, with some of Craigs friends, and stay up all night, dancing in a drug-fueled trance.

Last edited by Moral Hazard on Apr-26-2011 at 07:48

quote:

Originally posted by cammaxwell You guys were screwing up because you calculating the %60/%40 from the 204g.......when the question was asking about the ORIGINAL pieces, not the final piece. Read the question again, and then look at your calculations. You should not be basing it on the final 204g........

Ahhhhhhh.....

Ok I see.......

Frickin idiot.....

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Originally posted by chinamon chinamon is INCH MOAN. LOL so fitting.