McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
6. Probabilities of Mutually Exclusive Events
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Exercise 39 Page 931

Remember that the event of drawing the first king affects the probability of drawing the second one.

Dependent or independent? Dependent.
Probability: 1221 or about 0.5 %

Practice makes perfect

The event of drawing the first king affects the probability of drawing the second one. This is because there is one fewer card from which to choose, and one fewer king to draw. Therefore, the events are dependent.

Probability of Dependent Events

If two events A and B are dependent, then the probability that A and B will occur is P(AandB)=P(A)* P(B|A)

Let's start by calculating the probability of drawing a king from a standard deck of cards.
A standard deck has 52 cards, four of which are kings. P(A)&=4/52 l←Number of kings ←Number of cards P(B|A) is the probability of drawing a king, given that the first card drawn is a king. Since we have already drawn a king, there are 51 cards, from which three of them are kings. P(B|A)&= 3/51 l←Remainingkings ←Remainingcards Finally, according to the formula, to calculate P(AandB) we have to multiply P(A) and P(B|A).
P(AandB)=P(A)* P(B|A)
P(AandB)= 4/52* 3/51
Simplify right-hand side
P(AandB)=1/13*3/51
P(AandB)=1/13*1/17
P(AandB)=1/221
Convert to percent
P(AandB)=0.004525...
P(AandB)≈0.005
P(AandB)≈0.5 %
Probability of the given event is equal to 1221 or about 0.5 %.