Word problem

[missc]

David has 2500 gallons of a commercial-grade hydrogen peroxide solution that is 60% pure hydrogen peroxide. How much distilled water (which is 0% hydrogen peroxide) will David need to add to this solution to create a new solution that is 25% pure hydrogen peroxide?

 

[Mrspi]

David has 2500 gallons of a commercial-grade hydrogen peroxide solution that is 60% pure hydrogen peroxide. How much distilled water (which is 0% hydrogen peroxide) will David need to add to this solution to create a new solution that is 25% pure hydrogen peroxide?

You haven't shown us anything that would help us know where you are coming from!

Have you defined a variable?

What are you asked to find?

Please show us SOMETHING that would indicate where you ARE in the thought process for solving this problem. Once we see that, we'll have a much better idea of how to help you.

 

[missc]

This is what I have:

quantity of distilled water added = x gallons
total amount of solution = 2500 + x

I don't know what to do after this...

 

[Mrspi]

This is what I have:

quantity of distilled water added = x gallons
total amount of solution = 2500 + x

I don't know what to do after this...

Ok!! That's a good start.

You start with 2500 gallons of solution which is 60% hydrogen peroxide. How much hydrogen peroxide is in this 2500 gallons?

60% of 2500 gallons = gallons of hydrogen peroxide at the beginningT

You add x gallons of water to this, which is 0% hydrogen peroxide. So...you haven't added ANY hydrogen peroxide.

But, at the end, you will have 2500 + x gallons of a solution that is 25% hydrogen peroxide. The number of gallons of hydrogen peroxide at the end, then, would be 25% of (2500 + x) gallons, or 0.25(2500 + x)

hydrogen peroxide at the beginning PLUS hydrogen peroxide added = hydrogen peroxide at the end

0.60(2500) + 0(x) = 0.25(2500 + x)

Ok....can you solve that equation for x? "x" represents the number of gallons of just water (no hydrogen peroxide in it)....

Check your answer. Is the number of gallons of hydrogen peroxide at the end the same as the number of gallons of hydrogen peroxide you started with?

If you're still having trouble, please repost, showing us ALL of the work you did, so we can see how best to help you.

 

[missc]

Ok, that was very helpful. Thanks!

 

[Denis]

  2500  @ .60
    x   @ .00
=============
2500+x  @ .25

I find with those that something like above helps...