Transcript 12.5 Probability of Independent and Dependent Events

12.5 Probability of Independent and
Dependent Events
Learning Goals
● Learn the difference between independent
and dependent events
● How to find the probability of each
Two events are independent if their
occurrences do not affect each other
Examples:
Flipping a coin twice to get both heads
Picking a card, then replacing it before you pick
another
Ex. Coin Toss: find the probability of …
2 Heads (H and H)
Heads then Tails (H and T)
3 Heads (HHH)
Ex. Wheel of Fortune: Find the probability of
spinning …
900$, then Bankrupt
900$, then 800$, then 700$
24 possibilities
Two events are dependent if their occurrences
affect each other
(We still multiply the probabilities together)
Examples:
Picking a face card, then an ace (without
replacement)
Probability that it is stormy on Monday, then it
will rain on Tuesday.
Ex. A bag has 7 red, 3 blue and 10 green
marbles. Find the probability that you pick …
(without replacement)
1) blue, then red
2) blue, then blue
Try. Find the probability of …
a. with replacement b. without replacement
1) A king, then a 3
2) A ace, then a number card (2, 3, 4, … 10)
3) A ace, then an ace, then another ace
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