Ruth has a beaker containing a solution of 800 mL of acid and 200 mL of water. She thinks the solution is a little strong, so she drains 150 mL from the beaker, adds 150 mL of water, and stirs the solution. Ruth thinks the solution is still too strong, so again she drains 150 mL from the beaker, and adds 150 mL of water. How many mL of water are now in the beaker?
150 * 0.80 ==120 mL is acid poured out
150 - 120 ==30 mL of water is poured out
200 - 30 + 150 ==320 ml - water content after first pour.
800 - 120 ==680 mL - is acid content after first pour.
320 / [320 + 680] ==32% is now water content
68% is now acid content.
150 * 0.32 ==48 mL of water is poured out the 2nd time
150 * 0.68 ==102 mL of acid is poured out the 2nd time
320 - 48 + 150 ==422 mL is water now.
680 - 102 ==578 mL is acid now.
