





x 
7 
10 
8 
4 
3 
y 
8 
11 
9 
5 
4 

a. 
Calculate the covariance between the variables.
(Negative value should be indicated by a minus sign. Round
your intermediate calculations to 4 decimal places and final answer
to 2 decimal places.)

b1. 
Calculate the correlation coefficient. (Round your
intermediate calculations to 4 decimal places and final answer to 2
decimal places.)

b2. 
Interpret the correlation coefficient. 
There is _____ no, a weak negative, a
weak positive, a strong negative, a perfect positive, a strong
positive relationship between x and y. 
_______________________________________________________________________________________
The National Sporting Goods Association (NSGA) conducted a
survey of the ages of individuals that purchased skateboarding
footwear. The ages of this survey are summarized in the following
relative frequency distribution. Assume the survey was based on a
sample of 200 individuals.

Age of User 
Percent 
Under 14 years old 
23 
14 to 17 years old 
40 
18 to 24 years old 
18 
25 to 34 years old 
7 
35 to 44 years old 
7 
45 to 64 years old 
5 

Calculate the mean and the standard deviation of the age of
individuals that purchased skateboarding shoes. Use 10 as the
midpoint of the first class. (Do not round intermediate
calculations. Round your answers to 2 decimal places.)



Mean 

Variance 

Standard deviation 


_______________________________________________________________________________________
A manager of a local retail store analyzes the relationship
between advertising and sales by reviewing the store’s data for the
previous six months.

Advertising (in $100s) 
Sales (in $1,000s) 
205 
129 
56 
44 
55 
43 
54 
42 
169 
139 
203 
127 

a. 
Calculate the mean of advertising and the mean of sales.
(Round your answers to 2 decimal places.)

b. 
Calculate the standard deviation of advertising and the standard
deviation of sales. (Round your answers to 2 decimal
places.)


Standard Deviation 
Advertising 

Sales 


c1. 
Calculate the covariance between advertising and sales.
(Round your answer to 2 decimal places.)

c2. 
Interpret the covariance between advertising and sales.





Positive correlation 

No correlation 

Negative correlation 

d1. 
Calculate the correlation coefficient between advertising and
sales. (Round your answer to 2 decimal
places.)

d2. 
Interpret the correlation coefficient between advertising and
sales.





Weak positive correlation 

No correlation 

Strong negative correlation 

Weak negative correlation 

Strong positive correlation 
