how much 60% soln to replace w/ pure antifreeze to get 80%

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kyandrajones

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The cooling system of a car has a capacity of 25 liters. If the system is currently filled with a mixture that is 60% antifreeze, how much of this mixture should be drained and replaced with pure antifreeze so that the system is filled with a solution that is 80% antifreeze? Answer this by stating how many liters should be drained and replace with pure antifreeze.
 
Re: i need help with this one too

kyandrajones said:
The cooling system of a car has a capacity of 25 liters. If the system is currently filled with a mixture that is 60% antifreeze, how much of this mixture should be drained and replaced with pure antifreeze so that the system is filled with a solution that is 80% antifreeze? Answer this by stating how many liters should be drained and replace with pure antifreeze.
Click to expand...

To start:

Name the variable to be found - the amount of mixture to be drained = D

So amount of mixture left = 25 - D

Amount (volume) of antifreeze is present in that mixture (left after draining - from above) = ???

Amount of antifreeze in the mixture - after filling up = ???

Please share with us your work/thoughts - so that we know where to begin to help you.
 
Re: i need help with this one too

i have no idea where to begin to get to the answer thats all the question say i know the beginning state what i am trying to get but not sure of the formula.
 
Re: i need help with this one too

Start by answering the questions I asked you - that should lead you to the solution.
 
Re: i need help with this one too

ok maybe i am a little slow but I do not know the volume of the antifreeze in the mixture or how to find it
 
Basic Percentage ...

If I have $25, and you want 60% of it, then are you able to calculate that amount?

~ Mark :|
 
Re: i need help with this one too

kyandrajones said:
ok maybe i am a little slow but I do not know the volume of the antifreeze in the mixture or how to find it
Click to expand...

You have a 60% mixture - does that help?

If you had 1 litre of mixture - amount of anti-freeze in that mixture would be = (1 * 60/100 = ) 0.6 litre

If you had 2 litre of mixture - amount of anti-freeze in that mixture would be = (2 * 60/100 = ) 1.2 litre

If you had (25-D) litre of mixture - amount of anti-freeze in that mixture would be = (25-D) * 60/100 litre

Now you are going to add 'D' litre of antifreeze into it - how much total anti-freeze does that make?.....................(1)

Your total volume of mixture is now 25 litre.......................................................................................(2)

Ratio of antifreeze in the 'new' mixture = (1)/(2).................................................................................(3)

This (3) must also be equal to 0.8 (=80%)

Solve for 'D'
 
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