SOLUTION: Assume that there are 21 homes in the Quail Creek area and four of them have a security system. Three homes are selected at random: a. What is the probability all three of

Question 1117932: Assume that there are 21 homes in the Quail Creek area and four of them have a security system. Three homes are selected at random:
a.
What is the probability all three of the selected homes have a security system? (Round the final answer to 4 decimal places.)
b.
What is the probability none of the three selected homes has a security system? (Round the final answer to 4 decimal places.)
c.
What is the probability at least one of the selected homes has a security system? (Round the final answer to 4 decimal places.)
d.
Did you assume the events to be dependent or independent?

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
a. (4/21)(3/20)(2/19)=0.0030
b. (17/21)(16/20)(15/19)=0.5113
c. At least one is 1-probability of none or 1-0.5113=0.4887
They are dependent in that once I pick a home, it changes the probability for the second choice to a conditional probability.
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