Can you help me do this?

[busdent]

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In a barrel, there are 60 pints of a solution that is 20% alcohol. How many pints of pure alcohol must be added to produce a solution that is 40% alcohol?

A. 12
B. 20
C. 24
D. 35
E. 50

Thanks

 

[Indie]

In a barrel, there are 60 pints of a solution that is 20% alcohol. How many pints of pure alcohol must be added to produce a solution that is 40% alcohol?

A. 12
B. 20
C. 24
D. 35
E. 50

Thanks

I could be wrong, but you have 60pts thats 20%, which means that it's 1/3 alcohol... 1/3 of 60 is 20pts.... so if you double it and add another 20pts of pure alcohol, it should be 40%...

 

[aranjuez]

60*0.2 = 12

So... we have 12 pints/60total

(12+x)/(60+x) = 0.4

Solve away. 20 more is the answer.

aranjuez

 

[busdent]

I thought if you have 60 pints, 20% alcohol, it would be 1/5 or 12 pints pure alcohol...i can't do it pass that point

 

[busdent]

cool thanks so much

 

[aranjuez]

You do have 12 pure. Look at my solution again.

 

[busdent]

i am wondering how do u know it would be (12+x)/(60+x) = 0.4

 

[aranjuez]

x is how much more pure you're adding. It adds onto the original 12 to make more pure, and to the denominator, which is the total. The goal is to make it 40%, or 0.4

 

[busdent]

nevermind..i got it, I think.


thanks for the explanation.

 

[aranjuez]

If you need more clarification, I'd be glad to help.

 

[busdent]

actually i got it finally..it was really bugging me but thanks so much for the clarification

 

[aranjuez]

No problem. Always glad to help.