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Chapter 7: Q. 55 (page 479)
Songs on an iPod Refer to Exercise 53 . How many songs would you need to sample if you wanted the standard deviation of the sampling distribution of to be 10 seconds? Justify your answer.
The sample should be 36 tracks if the sampling distribution's standard deviation is 10 seconds.
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The manufacturer of a certain brand of aluminum foil claims that the amount of foil on each roll follows a Normal distribution with a mean of square feet (ft2 ) and a standard deviation of ft2 . To test this claim, a restaurant randomly selects 10 rolls of this aluminum foil and carefully measures the mean area to be.
a. Find the probability that the sample mean area is or less if the manufacturer鈥檚 claim is true.
b. Based on your answer to part (a), is there convincing evidence that the company is overstating the average area of its aluminum foil rolls?
Iced tea On Tuesday, the bottles of Arizona Iced Tea filled in a plant were supposed to contain an average of ounces of iced tea. Quality control inspectors selected bottles at random from the day鈥檚 production. These bottles contained an average of ounces of iced tea. Identify the population, the parameter, the sample, and the statistic.
Exercises 77 refer to the following setting. In the language of government statistics, you are "in the labor force" if you are available for work and either working or actively seeking work. The unemployment rate is the proportion of the labor force (not of the entire population) that is unemployed. Here are estimates from the Current Population Survey for the civilian population aged 25 years and over in a recent year. The table entries are counts in thousands of people.
Unemployment (1.1) Find the unemployment rate for people with each level of education. Is there an association between unemployment rate and education? Explain your answer.
The five-number summary for a data set is given by min = 5, , median = 20, , max = 75. If you wanted to construct a boxplot for the data set that would show outliers, if any existed, what would be the maximum possible length of the right-side 鈥渨hisker鈥�?
a. 33
b. 35
c. 45
d. 53
e. 55
More homework Some skeptical Ap庐 Statistics students want to investigate the newspaper's claim in Exercise , so they choose an SRS of students from the school to interview. In their sample, students completed their homework last week. Does this provide convincing evidence that less than of all students at the school completed their assigned homework last week?
a. What is the evidence that less than of all students completed their assigned homework last week?
b. Provide two explanations for the evidence described in part (a).
We used technology to simulate choosing SRSs of size from a population of students where completed their assigned homework last week. The dotplot shows the sample proportion of students who completed their assigned homework last week for each of the simulated samples.
c. There is one dot on the graph at . Explain what this value represents.
d. Would it be surprising to get a sample proportion of or smaller in an SRS of size when ? Justify your answer.
e. Based on your previous answers, is there convincing evidence that less than of all students at the school completed their assigned homework last week? Explain your reasoning.
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