MATH 221 STATISTICS FOR DECISION MAKING WEEK 7 HOMEWORK / 2020
DeVry MATH 221 Week 7 Homework Answers (2020)
1. Two variables have a positive non-linear correlation. Does the dependent variable increase or decrease as the independent variable increases?
2. What does the variable r2 represent?
3. A baseball player wants to determine if the type of bat he uses each year can be used to predict the amount of improvement in his game. Which variable would be the response variable?
4. Two variables have a negative linear correlation. Where would the y-intercept of the regression line be located on the y-axis?
5. A value of the dependent variable that corresponds to the value of xi would be given the notation of:
6. If there is a ^, or hat, above a variable, what does that mean?
7. Which of the following graphs displays the regression equation of ŷ=1.41x + 3.16?
8. Find the regression equation for the following data set
x
|
143
|
167
|
143
|
189
|
122
|
174
|
134
|
155
|
y
|
60
|
80
|
72
|
69
|
44
|
59
|
51
|
63
|
9. A data set whose original x values ranged from 41 through 78 was used to generate a regression equation of ŷ=5.3x – 21.9. Use the regression equation to predict the value of y when x=70.
10. A data set whose original x values ranged from 120 through 351 was used to generate a regression equation of ŷ=0.06x + 14.2. Use the regression equation to predict the value of y when x=110.
11. Find the regression equation for the following data set
x
|
7
|
8
|
5
|
9
|
4
|
3
|
9
|
6
|
7
|
8
|
y
|
4
|
2
|
8
|
3
|
7
|
9
|
3
|
5
|
6
|
3
|
12. A data set whose original x values ranged from 137 through 150 was used to generate a regression equation of ŷ=-4.5x + 51. Use the regression equation to predict the value of y when x=139.
13. If the linear correlation coefficient is 0.681, what is the value of the coefficient of determination?
14. If the linear correlation coefficient is -0.156, what is the value of the coefficient of determination?
15. If the coefficient of determination is 0.497, what percentage of the data about the regression line is explained?
16. If the coefficient of determination is 0.822, what percentage of the data about the regression line is unexplained?
17. What is the primary difference between a simple linear regression and a multiple linear regression?
18. The equation used to predict how tall a dog will be as an adult is ŷ=4.5 + 0.7x1 + 0.55x2, where x1 is the height of the mother and x2 is the height of the father. Use this equation to predict the height of a puppy whose mother is 41.3 inches tall and whose father is 44.9 inches tall.
19. The equation used to predict how long it will take to receive a package through the mail is ŷ=0.5 + 0.02x1 + 0.85x2
days, where x1 is the distance to travel and x2 is the weight of the package. Use this equation to predict the how long it will take to receive a package that is 224 miles away and weighs 2.2 pounds.
days, where x1 is the distance to travel and x2 is the weight of the package. Use this equation to predict the how long it will take to receive a package that is 224 miles away and weighs 2.2 pounds.
20. The equation used to predict how long a cold will last is ŷ=-1.8 + 0.09x1 + 3.2x2 – 1.9x3, where x1
is person’s temperature on the first day, x2 is number of people seen each day, and x3 is the amount of sleep the person gets. Use this equation to predict how long a cold will last with a temperature of 100.4 degrees, an average of 6 people seen each day, and 4 hours of sleep.
is person’s temperature on the first day, x2 is number of people seen each day, and x3 is the amount of sleep the person gets. Use this equation to predict how long a cold will last with a temperature of 100.4 degrees, an average of 6 people seen each day, and 4 hours of sleep.
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