Chapter 5 Test B
Name: ______Date: ______
1. / In a survey, 85% of the voters support a particular referendum. If 40 voters are chosen at random, and X is the number of voters that support this referendum, find the standard deviation of X.2. / In a survey, 55% of the voters support a particular referendum. If 40 voters are chosen at random, and X is the number of voters that support this referendum, find the mean and variance of X.
3. / A school is sending 11 children to a camp. If 20% of the children in the school are first graders, and the 8 children are selected at random, what is the mean and variance of the number of first graders chosen?
4. / If 1.5% of the bolts made by an automotive factory are defective, what is the probability that in a shipment of 200 bolts, there are 6 defective bolts?
5. / The figure below represents the probability distribution for selecting a number of objects out of a container. Construct a probability distribution from this graph.
6. / Draw a graph showing the probability distribution for the sample space for tossing four coins.
7. / The number of song requests a radio station receives per day is indicated in the table below. Construct a graph for this data.
Number of calls, / 8 / 9 / 10 / 11 / 12
Probability, / 0.21 / 0.31 / 0.16 / 0.14 / 0.18
8. / For the following data, construct a graph showing the probability distribution.
/
0 / 0.35
1 / 0.25
2 / 0.20
3 / 0.15
4 / 0.05
9. / A pet supplier has a stock of parakeets of which 30% are blue parakeets. A pet store orders 3 parakeets from this supplier. If the supplier selects the parakeets at random, what is the chance that the pet store gets exactly one blue parakeet?
10. / Why is the following distribution not a probability distribution?
x / -5 / -4 / -3 / -2 / -1
P(x) / 0.19 / 0.16 / –0.10 / 0.48 / 0.27
11. / On a Saturday evening, 34% of the people in Chicago go out to dinner, 18% see a movie, 13% have a party, and 35% stay home. Seventeen people are randomly selected. Can the probability that exactly 4 of them stay home be computed using a binomial model?
12. / There are 50,000 people at a stadium watching a soccer match, and 40,000 of them are male. If 2 people are chosen at random, what is the probability that both of them are male?
13. / What probability value would complete the following probability distribution?
x / -3 / -2 / -1 / 0 / 1 / 2
P(x) / 0.09 / 0.21 / -0.02 / p / 0.17 / 0.25
14. / A university has 10,000 students of which 6000 are male and 4000 are female. If a class of 30 students is chosen at random from the university population, find the mean and variance of the number of male students.
15. / A multiple choice quiz consists of 7 questions, each with 3 possible answers. If a student guesses at the answer to each question, then what is the mean number of correct answers?
16. / What probability value would be needed to complete the following probability distribution?
x / -5 / -1 / 0 / 1 / 4
P(x) / 0.12 / 0.24 / 0.12 / 0.24
17. / If the possible values of a random variable X are between -1 and 6, is the mean of X positive or negative?
18. / A researcher calculated the values and probabilities for a random variable X as shown below. Unfortunately, he erased the last value and needs to figure it out. If the mean of X was 2.2, then what was the last value?
x / 0 / 1 / 3 / ?
P(x) / .4 / .1 / .2 / .3
19. / A researcher wished to conduct a survey of college students to study their opinion about the proposed change in smoking rules. The researcher asked a group of 20 students – 11 of them supported the change, 6 of them did not, and 3 had no opinion. This is not a binomial model because
20. / Find the mean of the distribution shown.
x / -3 / -2 / -1 / 0
P(x) / 0.20 / 0.24 / 0.47 / 0.09
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