+585 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 $300$ mL from the beaker, adds $300$ mL of water, and stirs the solution. Ruth thinks the solution is still too strong, so again she drains $300$ mL from the beaker, and adds $300$ mL of water. How many mL of water are now in the beaker?
+129771 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 $300$ mL from the beaker, adds $300$ mL of water, and stirs the solution. Ruth thinks the solution is still too strong, so again she drains $300$ mL from the beaker, and adds $300$ mL of water. How many mL of water are now in the beaker?
The mixture originally is 80% acid and 20% water
When she drains 300 ml there are 700 ml composed of (.80)(700) = 560ml of acid and (.20)(700) = 140ml of water
Adding 300 ml of water to this gives a solution composed of 560/1000 = 56% acid and (140 + 300) /1000 =
44% water ......so 560 ml are acid and 440ml are water
Draining 300 ml of this solution gives us ( .56)(700) = 392ml of acid and (.44)(700) = 308ml of water
Adding back 300ml of water gives us 308 + 300 = 608ml of water
