STAT 200 Week 6 Homework Assignment Summer 2017 5. Illowsky Page 621 Problem 130 / Page 663, Problem 130:
For a chi-square distribution:
a. Explain why the goodness-of-fit test and test for independence are generally right-tailed.
b. If you did a left-tailed test, what would you be testing? 7. Illowsky Page 673 Problem 69 / Pages 717-718, Problem 69: Recently, the annual number of
driver deaths per 100,000 for the selected age groups was as follows:
Age
17.5
22
29.5
44.5
64.5
80 Number of Driver Deaths Per 1000
38
36
34
20
18
28 a. For each age group, pick the midpoint of the interval for the x value. (For the 75+ group, use 80.)
IGNORE 7a
b. Using “ages” as the independent variable and “Number of driver deaths per 100,000” as the
dependent variable, make a scatter plot of the data.
c. Calculate the least squares (best–fit) line. Put the equation in the form of ? = a + bx
d. Find the correlation coefficient. Is it significant?
e. Predict the number of deaths for ages 40 and 60.
f. Based on the given data, is there a linear relationship between age of a driver and driver fatality
rate? g. What is the slope of the least squares (best-fit) line? Interpret the slope. * * * * * * * * 1 * * * * * STAT 200 Week 6 Homework Assignment Summer 2017 8. Illowsky Page 679 Problem 81 / Pages 724-725, Problem 81: The percent of female wage and salary
workers who are paid hourly rates is given below for the years 1979 to 1992:
Year
1979
1980
1981
1982
1983
1984
1985
1986
1987
1990
1992 Percent of workers paid hourly rates
61.2
60.7
61.3
61.3
61.8
61.7
61.8
62.0
62.7
62.8
62.9 a. Using “year” as the independent variable and “percent” as the dependent variable, draw a
scatter plot of the data.
b. Does it appear from inspection that there is a relationship between the variables? Why or why
not?
c. Calculate the least-squares line. Put the equation in the form of: ? = a + bx
d. Find the correlation coefficient. Is it significant?
e. Find the estimated percents for 1991 and 1988.
f. Based on the data, is there a linear relationship between the year and the percent of female
wage and salary earners who are paid hourly rates? g. Are there any outliers in the data?
h. What is the estimated percent for the year 2050? Does the least-squares line give an accurate
estimate for that year? Explain why or why not.
i. * What is the slope of the least-squares (best-fit) line? Interpret the slope. * * * * * * * 2 * * * * * STAT 200 Week 6 Homework Assignment Summer 2017 9. Lane Page 511 Problem 6: For the data in the following table,
x
4
3
5
11
10
14 y
6
7
12
17
9
21 Compute: r and determine if it is significantly different than 0 Compute slope of the regression line and if it is significantly different than 0 Compute 95% confidence interval for the slope: 3
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