math Question ( Percentages / Diluent )?
How many mL of water should be added to 480mL of 70% solution to prepare a 30% solution?
How do you go about doing this I completely forgot?
It's not 4!
I know the answer, I just don't know how to do it...
- Anonymous8 years agoFavorite Answer
If you have 480mL of 70% solution, this means that 70% of 480mL is the solute and the rest (30%) is the solvent (water). How much solute is there? Perform this calculation to find out.
(70*480)/100 = 7*48 = 346g
This is important because we want 346 to be 30% of our final solution. If it is, how much final solution is there? If we let x represent the unknown amount of the final solution then
346/x = 30/100.
We can multiply both sides by 100, divide both sides by 30 and multiply both sides by x to get
346 * 100 / 30 = x.
You calculate this with a machine if you can't do it by hand to get
x = (1153 + 1/3) mL = 1153.3333... mL
Now, that is the final amount of solution and you already have 480mL so you still need
(1153.3333.... - 480)mL = 673.333... mL
- 8 years ago
Bro, it's 4.
Trust me, I'm a doctor.Source(s): I went to doctor's school.