Problem 27E

Blood Types The probability that a person in the United States has type B+ blood is 9%. Five unrelated people in the United States are selected at random. (Source: American Association of Blood Banks)

(a) Find the probability that all five have type B+ blood.

(b) Find the probability that none of the five have type B+ blood.

(c) Find the probability that at least one of the five has type B+ blood.

(d) Which of the events can be considered unusual? Explain.

Answer

Step 1 of 4

(a)

The probability that a person in the U.S. has type B+ blood is 9%.

Five unrelated people in the U.S. are selected at random.

We are asked to find the probability that all five have type B+ blood.

Using independence rule of probability, we can write the probability that all five have type B+ blood,

[since the probability that a person in the U.S. has type B+ blood is 9% or 0.09]

Hence the probability is