ST361 HW1 (due Thursday, 9/5/13)
(a) Show your work in order to earn the full credit. This means that you have to present
your steps or explain your reasoning for the answers you obtain, rather than just to
write down the answer itself.
Note that answers without steps or reasoning will receive 0 credits even if the answers
are correct!
(b) Remember to staple your homework and write your name on your homework. You’ll
lose 5 points if not.
1) The manager of a used car lot would like to know what proportion of each type of
truck has been sold in the last month. The results of his study are listed below for 35
trucks sold last month, where 1=Ford, 2=four-wheel drive Ford, 3=Chevy, 4=fourwheel drive Chevy, 5=Dodge, and 6=four-wheel Dodge.
5,1,1,2,3,
2,5,5,3,4,
1,1,2,3,3,
5,4,4,2,1,
5,6,5,3,4,
1,6,1,2,6,
2,1,1,6,3
(a) What is the population of this study and what is the sample of this study
(b) What is the variable of interest in this data set? What is the type of this variable?
(c) Construct a relative frequency table for the type of truck sold in the last month.
(d) What proportion of the trucks sold were four-wheel drive trucks?
(e) Use an appropriate graphical presentation for this data set.
(f) Based on your answers in (d) and (e), what can you infer on the proportion of the
types of truck sold in Japan?
2) 1.15 (a) (p.22)
3) 2.2 (p.68) In part (a) and (c) ignore the parts about “trimmed mean”
4) 2.3 (p.68) For this question, assume that we are only given the stem-and-leaf plot as
shown in Question 2.35 (p.86) rather than the actual data points listed
here.
(a) How does the stem-and-leaf plot suggest that the sample mean and
median will compare?
(b) Do (b)
(c) Do (d)
5) 2.19 (p.77)
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