Conditional Probability Worksheet
This worksheet covers conditional probability concepts for Grade 9 students, including calculating probabilities of events given another event has occurred.
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Conditional Probability Worksheet
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Read each question carefully and answer to the best of your ability. Show all your work for full credit.
1. A bag contains 5 red marbles and 3 blue marbles. If two marbles are drawn without replacement, what is the probability that the second marble drawn is blue, given that the first marble drawn was red?
3/8
3/7
5/8
5/7
2. In a class, 60% of students study Math and 40% study Science. If 20% of students study both Math and Science, what is the probability that a randomly selected student studies Science given that they study Math?
0.20
0.33
0.50
0.60
3. The formula for conditional probability P(A|B) is P(A ∩ B) / P( ).
4. If two events A and B are independent, then P(A|B) = P( ).
5. A standard deck of 52 cards is used. What is the probability that a randomly drawn card is a King, given that it is a face card?
6. A family has two children. What is the probability that both children are girls, given that at least one of them is a girl?
Use the Venn Diagram below to answer the following questions.
7. Find P(A).
8. Find P(B).
9. Find P(A|B).
10. Find P(B|A).
11. If P(A|B) = P(A), then events A and B are independent.
True
False
12. Conditional probability is always less than or equal to the probability of the conditioned event.
True
False