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by Target2009 » Fri Jan 07, 2011 9:17 pm
@towerSpider : please paste the question instead of link.

A chemist has one solution that is 30% pure salt and another is 60% pure salt. how many ounces of each solution must he use to produce 60 ounces of a solution that is 50 % salt.

Sol1 - s1
Sol2 - s2
Total = 60
s2 = 60 - s1
0.3 * s1 + 0.6 * s2 = 0.5 * 60
0.3 * s1 + 0.6 *(60 - s1) = 0.5 * 60
36 - 0.3 s1 = 30
0.3s1 = 6
S1 = 20
S2 = 60 - 20 = 40

Sol1 = 20 Oz
sol2 = 40 Oz
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by bblast » Sat Jan 08, 2011 12:38 am
target2k9

this question can be solved even faster using "alligation rule"

I guess u would be aware of that already ?
Cheers !!

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by bblast » Sat Jan 08, 2011 12:39 am
btw nice link towerspider

thanks
Cheers !!

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by Night reader » Mon Jan 10, 2011 1:50 pm
Target2009 wrote:@towerSpider : please paste the question instead of link.

A chemist has one solution that is 30% pure salt and another is 60% pure salt. how many ounces of each solution must he use to produce 60 ounces of a solution that is 50 % salt.

Sol1 - s1
Sol2 - s2
Total = 60
s2 = 60 - s1
0.3 * s1 + 0.6 * s2 = 0.5 * 60
0.3 * s1 + 0.6 *(60 - s1) = 0.5 * 60
36 - 0.3 s1 = 30
0.3s1 = 6
S1 = 20
S2 = 60 - 20 = 40

Sol1 = 20 Oz
sol2 = 40 Oz
I am solving this problem with the use of alligation alternate method to avoid lengthy arithmetic calculations...

We want to find the amount of two ingredients to mix together to form a mixture with a given amount of pure salt solution.

There are only two ingredients: 30% pure salt and 60% pure salt - there is only one possible way to form a pair. The difference of 30% from the desired 50%, 20%, is assigned to the 60% pure salt, and the difference of 60% from the desired 50%, 10%, is assigned alternately to the 30% pure salt. The total amount, 60 ounces, is then divided by the sum 20 + 10 (%%) = 60/30 to yield 2, and the amounts of the two ingredients are 2*20=40 ounces of 60% pure salt and 2*10=20 ounces of 30% pure salt.

The key to approaching any problem with the alligation alternate method would be usage of hi-low method i.e. switching between high and low volume capacities.
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