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Chapter 7: Q. 18 (page 463)
Records from a random sample of dairy farms yielded the information below on the number of male and female calves born at various times of the day.
What is the probability that a randomly selected calf was
born in the night or was a female?
(a)
(b)
(c)
(d)
(e)
The correct answer is option (a).
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If we take a simple random sample of size from a population of size , the variability of our estimate will be
(a) much less than the variability for a sample of size from a population of size .
(b) slightly less than the variability for a sample of size from a population of size .
(c) about the same as the variability for a sample of size from a population of size .
(d) slightly greater than the variability for a sample of size from a population of size .
(e) much greater than the variability for a sample of size from a population of size .
Students on diets A sample survey interviews an SRS of college women. Suppose (as is roughly true) that of college women have been on a diet within the past months. What is the probability that or more of the women in the sample have been on a diet? Follow the four-step process.
AP2.24. Every years, swarms of cicadas emerge from the ground in the eastern United States, live for about six weeks, and then die. (There are several different 鈥渂roods,鈥� so we experience cicada eruptions more often than every years.) There are so many cicadas that their dead bodies can serve as fertilizer and increase plant growth. In a study, a researcher added cicadas under randomly selected plants in a natural plot of American bell flowers on the forest floor, leaving other plants undisturbed. One of the response variables measured was the size of seeds produced by the plants. Here are the box plots and summary statistics of seed mass (in milligrams) for cicada plants and undisturbed (control) plants:
Variable: n Minimum Q1 Median Q3 Maximum
Cicada plants: 39 0.17 0.22 0.25 0.28 0.35
Control plants: 33 0.14 0.19 0.25 0.26 0.29
(a) Is this an observational study or an experiment? Explain.
(b) Based on the graphical displays, which distribution has
the larger mean? Justify your answer.
(c) Do the data support the idea that dead cicadas can
serve as fertilizer? Give graphical and numerical evidence
to support your conclusion.
For Exercises 1 to 4, identify the population, the parameter, the sample, and the statistic in each setting
Hot turkey Tom is cooking a large turkey breast for a holiday meal. He wants to be sure that the turkey is safe to eat, which requires a minimum internal temperature of . Tom uses a thermometer to measure the temperature of the turkey meat at four randomly chosen points. The minimum reading in the sample is
For Exercises 1 to 4, identify the population, the parameter, the sample, and the statistic in each setting.
Gas prices How much do gasoline prices vary in a large city? To find out, a reporter records the price per gallon of regular unleaded gasoline at a random sample of gas stations in the city on the same day. The range (maximum-minimum) of the prices in the sample is cents
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