Probability of Dependent Events

Students learn that two events are dependent if the outcome of the first event affects the outcome of the second event. For example, taking a block out of a jar, then taking a second block out of a jar. And the probability of dependent events can be found by multiplying the probability of the first event times the probability of the second event. For example, if there are 4 blue blocks and 4 yellow blocks in a jar, the probability of taking a blue block out of the jar then a yellow block out of the jar is 4/8 times 4/7, or 16/56, which reduces to 2/7. The reason that the probability of taking a yellow block out of the jar is 4/7 rather than 4/8 is that a blue block has already been taken out, so there are only 7 blocks left in the jar.