There are four blood types, and not all are equally likely to be in blood banks. 49% of donations are type O blood, 27% of donations are type A blood, 20% of donations are type B blood, and 4% of donations are type AB blood. A person with type A blood can safely receive blood transfusions of type O and type A blood. What is the probability that if 3 donations are made, all 3 of them can be safely used in a blood transfusion on someone with type A blood?
C
(0.27)3 + (0.49)3 = 0.1373A person with type A blood can receive donations that are type O or type A. The probability that one donation is usable is 0.49 + 0.27 = 0.76. For all 3 donations to be usable, multiply that probability three times: (0.76)³ = 0.438976, or about 0.4390, matching choice D.
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