Blood types: The blood type O negative is called the

Last updated: 7/23/2022

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 20 donors. Round the answers to at least four decimal places. (a) What is the probability that two or more of them have type O negative blood? The probability that two or more of them have type O negative blood is 0.2642 (b) What is the probability that fewer than four of them have type O negative blood? The probability that fewer than four of them have type O negative blood is 0.9841 (c) Would it be unusual if none of the donors had type O negative blood? Use a cutoff of 0.05.