
Directions: Read carefully. Answers are rounded to nearest hundredths, unless stated otherwise.
1. Manatees are large, fully aquatic, highly intelligent, herbivorous marine mammals who must surface regularly for air. Marine biologists fear that the number of registered powerboats threatens the existence of manatees, as the animals are injured or killed by hitandruns and propellers.



The chart at the right contains data collected from one location.
Prepare a linear regression model.
(Powerboats on xaxis, Manatees on yaxis.)
a) What is the slope of the best fit linear regression equation?

Year 
Powerboat registration
(in 1000s) 
Manatees Killed 
2005 
314 
54 
2006 
351 
70 
2007 
415 
95 
2008 
469 
125 
2009 
522 
140 
2010 
574 
167 

c) Which is better for the manatees, positive residuals or negative residuals?
d) What does the model suggest regarding the future of the manatees?


2. The table below shows the ages of eight cows (in years) and their milk production (in gallons) per week.
Prepare a linear regression model.
(Cow's Age on xaxis, Milk on yaxis.)
a) Which type of correlation exists for this data?
b) Which equation is the best fit linear regression equation for this data, rounded to nearest hundredths?

Cow's Age 
Gallons of Milk per Week 
4 
37.2 
5 
35.2 
6 
33.6 
7 
33.2 
7 
32.8 
8 
33.1 
9 
31.6 
10 
29.8 

c) What is the slope of the regression line telling us?
d) What is the yintercept telling us?


3. A survey of 16 shoppers at a mall was tallied to show their ages (in years) and the number of movies they saw over the past year.
Prepare a linear regression model.
(Age on xaxis, Movies on yaxis.)
a) Which type of correlation exists for this data?
b) What is the slope of the best fit linear regression equation?
c) What is the yintercept of the best fit linear regression equation?
d) Using the regression equation, predict the number of movies that would be seen in one year by a 9 year old.

Age
(years)

Number of Movies 
18 
24 
24 
11 
17 
24 
24 
16 
26 
9 
25 
8 
17 
28 
19 
20 
16 
30 
20 
16 
18 
25 
22 
20 
22 
12 
25 
12 
21 
13 
23 
14 

e) What is the slope of the regression line telling us?


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