hai help plz

• June 8th 2006, 03:21 PM
Aarxn
hai help plz
One kind of hard candy sells for 89 cent per kilogram. Another sells for $1.10 per kilogram. How many kilograms of each kind will be used for 30 kilograms of a mixture to sell for 96 cent per kilogram? How many millileters of vinegar must be added to 20 milliters of a 10%-vineger solution to make it a 25% vinegar solution? How would I solve these? • June 8th 2006, 03:29 PM ThePerfectHacker Quote: Originally Posted by Aarxn One kind of hard candy sells for 89 cent per kilogram. Another sells for$1.10
per kilogram. How many kilograms of each kind will be used for 30 kilograms of a mixture to sell for 96 cent per kilogram?

Let us say you sell $x$ kilograms of candy which goes for .89 and $y$ kilograms of candy which goes for 1.10 then the total price is,
$.89x+1.1y=30(.96)=28.8$
and the total amout is,
$x+y=30$
In this equation solve for "y",
$y=30-x$ thus, substitute that into the first equation,
$.89x+1.1(30-x)=28.8$
Open parantheses,
$.89x+33-1.1x=28.8$
Subtract 33 from both sides and combine "x" terms,
$-.21x=-4.2$
Divide both sides by (-.21) thus,
$x=20$ thus, $y=10$
• June 8th 2006, 03:35 PM
ThePerfectHacker
Quote:

Originally Posted by Aarxn
How many millileters of vinegar must be added to 20 milliters of a 10%-vineger solution to make it a 25% vinegar solution?

Here is the formula,
$\mbox{concetration}=\frac{\mbox{amout of substance}}{\mbox{total amount present}}$

You have 20 milliletrs of 10% vineger solution. Meaning 10% of 20 is vineger thus, 2 milliletrs of vineger. You add $m$ millileters to get a concentration of 25% meaning,
$\frac{2+m}{20+m}=.25$
Note, and understand why the numerator is the way it is and the denominator is the way is it.

Now cross mutiply considering .25 as a fraction 1/4 thus,
$4(2+m)=20+m$
Thus,
$8+4m=20+m$
Subtract 8 and m from both sides,
$3m=12$
Thus,
$m=4\mbox{ millilters}$ need to be added.
• June 8th 2006, 03:56 PM
Aarxn
Quote:

Originally Posted by ThePerfectHacker
Here is the formula,
$\mbox{concetration}=\frac{\mbox{amout of substance}}{\mbox{total amount present}}$

You have 20 milliletrs of 10% vineger solution. Meaning 10% of 20 is vineger thus, 2 milliletrs of vineger. You add $m$ millileters to get a concentration of 25% meaning,
$\frac{2+m}{20+m}=.25$
Note, and understand why the numerator is the way it is and the denominator is the way is it.

Now cross mutiply considering .25 as a fraction 1/4 thus,
$4(2+m)=20+m$
Thus,
$8+4m=20+m$
Subtract 8 and m from both sides,
$3m=12$
Thus,
$m=4\mbox{ millilters}$ need to be added.

Hey, thank you for helping me.