Discuss the following:
1. Identify the type of sampling (random, stratified, systematic, cluster, convenience) used in each of the following AND state whether the sample results are likely to reflect the population from which the sample was drawn.
a. ______________________ Each hundredth hamburger manufactured is checked to determine its fat content.
b. ______________________ Mail carriers of a large city are divided into four groups according to gender (male or female) and according to whether they walk or ride on their routes. Then 10 are selected from each groups and interviewed to determine whether they have been bitten by a dog in that last year.
2. Seven runners ran a race, their times (in minutes) to complete it were as follows: Determine the indicated values.
8 11 13 7 6 8 10
a) variance s2=
b) standard deviation s=
3. A psychologist developed a test intended to measure the aggressiveness of drivers. The scores on the test have a mean of 250 and a standard deviation of 93. Is a score of 630 unusual? Why or why not?
4. A professor gives two different versions of a test. Version A results in scores with a mean of 78 and a standard deviation of 16. Version B results in scores with a mean of 52 and a standard deviation of 12. Which score is relatively better: 70 on Version A, or 50 on Version B? Explain your choice.
5. The ages of 20 dancers who responded to a call to audition for a musical comedy are listed in the box below. Use the raw data set to answer the listed questions.
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19 21 23 35 18 19 21 19 27 30
18 19 20 25 26 22 18 31 26 22
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a) Find Q2 for the data.
b) What is the 30th percentile?
c) Would you use the Empirical Rule or Chebyshev's Theorem to describe the distribution of this data? Explain your choice.
d) What percent of this data set is within two standard deviations of the mean?
e) If you were to group the data into classes using the interval 17 to 21 as the first class how many data would be in the third class?
6. Given the following frequency table:
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Absences
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Frequency
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Relative
Frequency
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Cumulative
Frequency
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0-9
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25
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10-19
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36
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20-29
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71
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30-39
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40
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40-49
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28
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a. What is the class width?
b. Fill in Relative and Cumulative Frequencies on the chart above.
c. What is the mean of the data?
7. If the variance of a set of data is 36, what is the standard deviation? ___________
8. The empirical rule states that if a distribution is bell-shaped approximately 95% of the data values fall with 2 standard deviations of the mean. The mean price of houses in a certain neighborhood is $90,000 and the standard deviations $10,000. Find the price range for which at least 95% of the houses will sell.