## The probability that a person in the United States has type B​+ blood is 10%. Four un-related people in the United States are selected at ra

Question

The probability that a person in the United States has type B​+ blood is 10%. Four un-related people in the United States are selected at random. ​1) Find the probability that all fourfour have type B​+ blood. 2) Find the probability that none of the five have type B+ blood. 3) Find the probability that at least one of the five has type B+ blood. 4) Which of the events can be considered unusual? Explain.A. None of these events are unusual.

B. The event in part​ (a) is unusual because its probability is less than or equal to 0.05.

C. The event in part​ (b) is unusual because its probability is less than or equal to 0.05.

D. The event in part​ (c) is unusual because its probability is less than or equal to 0.05.

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1 month 2021-09-21T06:55:09+00:00 1 Answer 0

1. a. 0.0001

b. 0.6561

c. 0.3439

d. B. The event in part​ (a) is unusual because its probability is less than or equal to 0.05.

Step-by-step explanation:

a. # We are given that the probability that a person in the United States has Type B+ blood = 0.10. Also we are told that four unrelated people in the United States are selected at random.

#We have to find here the probability that all four have type B+ blood.

Since the events are independent, we have :

Probability that all four have B+ blood  = 0.10 x 0.10x 0.10×0.10

= 0.0001

Therefore, the probability that all four have type B+ blood is 0.0001

b. We have to find the probability that none have B+ blood. Using the complementary law of probability we have:

Probability that blood type is not B+ = 1 – 0.10= 0.90

Therefore, the probability that none have B+ blood

= 0.90 x 0.90 x 0.90×0.90=0.6561

Therefore, the probability that none have B+ blood is 0.6561

c. We have to find the probability that at least one of the four have B+ blood.

#The probability that at least one of the four have B+ blood = 1 –  Probability that none have B+ blood type

=1-0.6561=0.3439

Therefore,the probability that at least one of the four has type B+ blood is 0.3439

d. An event is considered unusual if the probability of the event is small or less than 0.05 . We note that event a is the only small probabilty and is less than 0.05.

a is thus considered unusual(the rest are all usual events)