Dependent Events
Two events are dependent if the outcome of the first event affects the outcome of the second event, so that the probability is changed.
Example :
Suppose we have 5 blue marbles and 5 red marbles in a bag. We pull out one marble, which may be blue or red. Now there are 9 marbles left in the bag. What is the probability that the second marble will be red?
It depends. If the first marble was red, then the bag is left with 4 red marbles out of 9 so the probability of drawing a red marble on the second draw is 4/9. But if the first marble we pull out of the draw is blue, then there are still 5 red marbles in the bag and the probability of pulling a red marble out of the bag is 5/9.
The second draw is a dependent event. It depends upon what happened in the first draw.
