Blood types: The blood type O negative is called the "universal donor" type because it is the only blood type that may safely be transfused into any person. Therefore, when someone needs a transfusion in an emergency and their blood type cannot be determined, they are given type O negative blood. For this reason, donors with this blood type are crucial to blood banks. Unfortunately, this blood type is fairly rare; according to the Red Cross, only 5%

of U.S. residents have type O negative blood. Assume that a blood bank has recruited 18

donors. Round the answers to at least four decimal places.

(a)What is the probability that three or more of them have type O negative blood?

The probability that three or more of them have type O negative blood is

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