SOLUTION: In a department store there are 120 customers, 90 of who will buy at least 1 item. If 5 customers are selected at random, one by one, find the probability that all will buy at lea

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Question 352829: In a department store there are 120 customers, 90 of who will buy at least 1 item. If 5 customers are selected at random, one by one, find the probability that all will buy at least 1 item.
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
In a department store there are 120 customers, 90 of who will buy at least 1 item. If 5 customers are selected at random, one by one, find the probability that all will buy at least 1 item.
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P(each of 5 buy at least one) = 1 - P(none of 5 buy at least one)
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Note: There are 30 who will not buy at least one item
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= 1 - 30C5/120C5
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= 1 - 0.0000007478
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= 0.999252....
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Cheers,
Stan H.