Review &
Preview
3.2.2
3-58.
Platelets provided by blood donors are needed to save the lives of people who are sick or injured.
Platelets also vary in healthy adults from 450 to 150 thousand per microliter. Assume the
probability of a randomly selected blood donor having not enough platelets in their blood to be a
donor is 0.05. The test to measure the number of platelets a potential donor is subject to
variation. The probability the test will be negative (indicating the person has too few platelets)
is 0.98 given that the potential donor has too few platelets, and 0.02 for a potential donor with
enough. If a randomly selected person is tested and the test result is negative, what is the
probability they actually have sufficient platelets to be considered a donor. tree diagram
