Topic: Practice Prob. Ch 8
Chapter 8 Practice Questions
1. Twenty percent of the employees of a company are college graduates. Of these, 75% are in supervisory position. Of those who did not attend college, 20% are in supervisory positions. What is the probability that a randomly selected supervisor is a college graduate?
2. A bag contains 1 white ball and 2 red balls. A ball is drawn at random. If the ball is white then it is put back in the bag along with another white ball. If the ball is red, then it is put back in the back along with another two red balls.
a) What is the probability of drawing the second ball that is red?
b) Find the probability that the second ball is red given that the first ball is white.
c) If the second ball drawn is red, what is the probability that the first ball was red?
3. Roll two fair dice
- What is the probability they do not show the same number? Use complementary set
- What is the probability that the sum is 7?
- What is the probability that the sum is not more than 3?
4. In a study to determine frequency and dependency of color blindness relative to females and males, 1000 people were chosen at random and the following result were recorded:
|
| Female [F] | Male [F’] | Total |
| Color Blind [C] | 2 | 24 | 26 |
| Normal [C’] | 518 | 456 | 974 |
| Total | 520 | 480 | 1000 |
a) Convert the table to a probability table by dividing each entry by 1000.
b) What is the probability that a person is a woman, given that the person is color-blind?
c) What is the probability that a person is color-blind, given that the person is a male?
d) Are the events color-blindness and male independent?
e) Are the events color-blindness and female independent?
5. A computer store sells three types of microcomputers, brand A, brand B and brand C. Of the computers they sell, 60% are brand A, 25% are brand B, 15% are brand C. They have found that 20% of the brand A computers, 15% brand B computers, 5% of brand C computers are returned for service during the warranty period. If a computer is returned for service during the warranty period, what is the probability that it is a brand C computer?
6. From the standard deck of 52 cards, what is the probability of obtaining a 5-cards hand:
a) of all five are diamond?
b) of 4 spades and 1 diamond?
7. Do # 24 on page 438
8. a) In a 4 child families, what is the probability of having 2 girls and 2 boys?
b) Of having only one boy and 3 girls?