SOLUTION: A shipment of 20 computer keyboards is rejected if 5 are checked for defects and at least 2 are found to be defective. If there are actually 7 defective keyboards, find the mean

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Question 1081715: A shipment of 20 computer keyboards is rejected if 5 are checked for defects and at least 2 are found to be defective.
If there are actually 7 defective keyboards, find the mean number of defective keyboards in the sample of 5 from the shipment of 20.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The probability overall is 0.35, 7/20.
E(X)=x*p(x)=5*0.35=1.75