SOLUTION: In a sample of 80 adults, 28 said that they would buy a car from a friend. Three adults are selected at random without replacement. Find the probability that none of the three woul

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Question 1123139: In a sample of 80 adults, 28 said that they would buy a car from a friend. Three adults are selected at random without replacement. Find the probability that none of the three would buy a car from a friend.
Found 2 solutions by ikleyn, rothauserc:
Answer by ikleyn(52767)   (Show Source): You can put this solution on YOUR website!
.
There are   =  = 82160 different ways to select three persons of 80.


If none of the three would buy a car from the friend, it means that all three are from the subset of 80-28 = 52 persons.


There are   =  = 22100 different ways to select three persons of 52.


The probability under the question is the ratio of these two integers:


    P =  = 0.2690 = 26.90%  (approximately).

Solved.



Answer by rothauserc(4718)   (Show Source): You can put this solution on YOUR website!
80 - 28 = 52 would not buy a car from a friend
:
Probability that 3 adults selected without replacement would not buy a car from a friend = (52/80) * (51/79) * (50/78) = 0.2689 is approximately 0.269
:
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