GMAT Problem Solving (PS) | A gum ball dispenser has 24 gum balls: 12 white and 12 black, which

First three gumballs dispensed were black. That info yields two changes:

1. The total number of gumballs decreases from 24 to 21; and

2. The number of black gumballs decreases from 12 to 9

What is the probability that the next two
...

---