Marbles in a Jar
You have a large jar containing 75 black and 75 white marbles. You also have access to an arbitrarily large amount of marbles that are not in the jar. You begin removing marbles from the jar according to the following rules.
Select 2 marbles from inside the jar at random.
If the chosen marbles are both white, remove them both and put a black marble from outside the jar into the jar.
If at least one of the chosen marbles is black, remove a black marble and put the remaining marble back into the jar.
You repeat this process until only 1 marble remains in the jar. What color is it?