ACT Preparation / Unit 15 ACT 1423 short lesson, about 20 seconds
Mutually Exclusive Events and the Addition Rule
Captions available
The idea
Mutually exclusive events cannot happen together, so P(A or B) = P(A) + P(B). In general, P(A or B) = P(A) + P(B) − P(A and B), subtracting the overlap.
In practice
A king or a queen: 4/52 + 4/52 = 8/52. A king or a heart: 4/52 + 13/52 − 1/52 = 16/52.
Where people slip
Mutually exclusive and independent are different ideas.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
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