To conduct a scientific experiment, students need to mix 90 mL of a 3% acid solution. They have a 1% and a 10% soulution available. How many mL of each of the two solution must they combine to pruduce 90mL of the 3% solution?

Answer 1

Theoretically they need 90ml & 3% = 2.7ml of 100% solution.
Let x=volume of 10% solution, then
90-x = volume of 1% solution.
x*10% + (90-x)*1% = 2.7
Multiply by 100:
10x + (90-x) = 270
Solve for x and check.
I get 20ml 10% and (90-20)ml 1%.