Probability Math Example 3

Follow the full solution, then compare it with the other examples linked below.

medium

A card is drawn at random from a standard

52

-card deck. What is the probability it is a heart or a king?

1
Hearts: $13$ , Kings: $4$ , but the King of Hearts is counted in both, so subtract $1$ .
2
$P(\text{heart or king}) = \frac{13 + 4 - 1}{52} = \frac{16}{52} = \frac{4}{13}$ .

Answer

P(\text{heart or king}) = \frac{4}{13}

The inclusion-exclusion principle prevents double-counting:

P(A \cup B) = P(A) + P(B) - P(A \cap B)

About Probability

Probability is a number between 0 and 1 (inclusive) that measures how likely an event is to occur, where 0 means impossible and 1 means certain.

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