McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
6. Probabilities of Mutually Exclusive Events
Continue to next subchapter

Exercise 8 Page 929

Can both events occur at the same time?

Mutually exclusive or not? Mutually exclusive.
Probability: 213 or about 15.4 %

Practice makes perfect

We want to determine whether the events are mutually exclusive and find the probability of their union. We will do these things one at a time.

Mutually Exclusive

Events that cannot occur at the same time are mutually exclusive. Mutually exclusive events have no outcomes in common. For example, because it is not possible to toss a coin and obtain heads and tails at the same time, these two events are mutually exclusive.

Rules for Probability
If A and B are mutually exclusive events, the probability that A and B will occur is P(AandB)=0. If A and B are not mutually exclusive events, the probability that A and B will occur is P(AandB)≠0.
Let A be drawing a jack and B be drawing a six from a standard deck of cards.

There is no card in the deck that is both a jack and a six. Therefore, A and B are mutually exclusive events.

Probability

Now we can find the probability that the card drawn is either a jack or a six.

Addition Rules for Probability
If A and B are mutually exclusive events, the probability that A or B will occur is P(AorB)=P(A)+P(B). If A and B are not mutually exclusive events, the probability that A or B will occur is P(AorB)=P(A)+P(B)-P(AandB).
We know that there are 52 cards in the deck. Out of these, 4 cards are jacks and 4 cards are numbered 6. Now, we can calculate P(A) and P(B). P(A)&=4/52 l← ← lJacks Total cards P(B)&=4/52 l← ← lCards number6 Total cards Finally, considering that A and B are mutually exclusive events, let's calculate P(AorB).
P(AorB)=P(A)+P(B)
P(AorB)=4/52+ 4/52
Simplify right-hand side
P(AorB)=8/52
P(AorB)=2/13
Convert to percent
P(AorB)=0.153846...
P(AorB)≈0.154
P(AorB)≈15.4 %
We found that P(Jack or6) is equal to 213 or about 15.4 %.