Question

Jane has 60 liters of 70% acid solution. How many liters of water must be added to form a solution that is 40% acid?

Answer 1

so acid/liters = percent of acid.

acid/60 = 0.7 Now solve for the amount of acid you have.

But now we want a 40% solution, so how many liters do we need?

acid/newliters = 0.4 Now solve for how many liters you want. We want newliters, but we only have liters, so take the difference and that's how many we need to add.

Answer 2

suppose u add x litres of water where x is some number.. now u have a total of 60litres + x litres of solution... but u did not add any acid so the acid is (as it was)= 70%of 60 litres i.e 42 litres and the new % of acid in the sol is 42*100/(60+x) which should now be equal to 40%. so finding x is easy... x= 45....