1. sses or contact lenses). Let C = vision correction and P(C) = .75. (1 pt.)

(a) If someone is randomly selected, what is the probability that person does not use vision correction? (Find P(C').) Find the probability of not C.

(b) If four different people are randomly selected, what is the probability that they all use vision correction?

(c) Would it be unlikely to randomly select four people and find that they all use vision correction? Why or why not?

Not unlikely or unusual because , probability is greater than 0.05

2.) The two-way table shows the classification of students in a statistics class by age and

dominant hand. A student who is ambidextrous use both hands equally well.

	Right-handed	Left-handed	Ambidextrous	Total
30 and Under	11	4	1	16
Over 30	12	2	0	14
Total	23	6	1	30

What is the probability that a randomly selected student in the class is over 30 given that

the student is right-handed? (1 pt.)

3.) In a statistics class of 28 students, 13 identified themselves as boys and 15 identified

themselves as girls. On a unit test, 5 boys and 6 girls received a grade of 90-100. If a

student is chosen at random from the class, what is the probability of choosing a girl or

a student with a grade 90-100? (.5 point)

4.) A mathematics teacher has a box of 11 calculators - three that are defective and eight

that are good. If two calculators are selected, what is the probability that both

calculators are defective? (.5 point)

5.) Professor Sopala has invented a new lie-detector machine and is testing it. One

hundred test subjects are told to lie, and the machine catches 80 of them in the

lie. Another hundred test subjects are told to tell the truth, but the machine

nevertheless thinks that 5 of them are lying. (2 pts.)

(a) Draw the tree diagram corresponding to this situation.

(b) Suppose a test subject is chosen at random from the 200, and the machine claims

that he lied. What is the probability that he did in fact lie? Use Bayes' Th.

(c) Suppose a test subject is chosen at random from the 200, and

the machine claims that he told the truth. What is the probability that he did in fact tell

the truth? Use Bayes' Th.