Chapter 2: Graphs, Charts, and Tables--Describing Your Data

56 CHAPTER 2 • GRAPHS, CHARTS, AND TABLES—DESCRIBING YOUR DATA
25 CFOs. Assume that data are in thousands of
dollars.
173.1 171.2 141.9 112.6 211.1 156.5 145.4 134.0
192.0 185.8 168.3 131.0 214.4 155.2 164.9 123.9
161.9 162.7 178.8 161.3 182.0 165.8 213.1 177.4
159.3
a. Using 11 classes, construct a cumulative frequency
distribution.
b. Determine the proportion of CFO salaries that
are larger than $175,000.
c. Determine the proportion of CFO salaries that
are at most $205,000 and at least $135,000.
2-16. The San Diego Union Tribune reported (“Mortgage
Interest Rates Rise,” September 16, 2005) that the
30-year fixed-rate mortgage rates had risen to an
average of 5.74% in September 2005. A sample of
mortgage rates in the San Diego area produced the
following interest rates:
5.84 5.73 5.58 5.69 5.84 5.68 5.73
5.79 5.77 5.67 5.76 5.70 5.70 5.66
5.71 5.80 5.81 5.75 5.81 5.78 5.79
5.77 5.73 5.67 5.74 5.76 5.76 5.74
5.73 5.71 5.71 5.72 5.80 5.69 5.88
5.70 5.75 5.75 5.68 5.72 5.70 5.67
5.83 5.76 5.80
a. Construct a histogram with eight classes beginning
at 5.58.
b. Determine the proportion of mortgage rates that
are at least 5.74%.
c. Generate an ogive for this data.
Computer Database Exercises
2-17. The Franklin Tire Company is interested in
demonstrating the durability of its steel-belted
radial tires. To do this, the managers have decided
to put four tires on 100 different sport utility
vehicles and drive them throughout Alaska.
The data collected indicate the number of miles
(rounded to the nearest 1,000 miles) that each
of the SUVs traveled before one of the tires on
the vehicle did not meet minimum federal
standards for tread thickness. The data file is
called Franklin.
a. Construct a frequency distribution and histogram
using 8 classes. Use 51 as the lower
limit of the first class.
b. The marketing department wishes to know
the tread life of at least 50% of the tires, the
10% that had the longest tread life, and the
longest tread life of these tires. Provide this
information to the marketing department.
Also provide any other significant items that
point out the desirability of this line of steelbelted
tires.
c. Construct a frequency distribution and histogram
using 12 classes, using 51 as the lower
limit of the first class. Compare your results
with those in parts a and b. Which distribution
gives the best information about the desirability
of this line of steel-belted tires? Discuss.
2-18. The United States Golf Association recently
conducted a survey of its members. Among other
questions, the members were asked to indicate the
number of 18-hole rounds that they played last
year. Data for a sample of 294 members is provided
in the data file called golf survey.
a. Using the 2 k n guideline, what is the minimum
number of classes that should be used to
display these data in a grouped data frequency
distribution?
b. Referring to part a, what should the class width
be, assuming you round the width up to nearest
integer?
c. Referring to parts a and b, develop a grouped
data frequency distribution for these golf
data.
d. Based on your answer to part c, construct
and interpret a frequency histogram for
the data.
2-19. J.D. Power and Associates’ annual customersatisfaction
survey, the Automotive Performance,
Execution and Layout (APEAL) Study SM , in its
10th year, was released on September 21, 2005.
The study measures owners’ satisfaction with
the design, content, layout, and performance of
their new vehicles. A file entitled APEAL contains
the satisfaction ratings for 2005 for each
make of car.
a. Construct a histogram for the APEAL
ratings that starts at 825 and has class widths
of 10.
b. The past industry average APEAL rating was
855. What does the 2005 data suggest in
terms of the relative satisfaction with the 2005
models?
c. Determine if any class is vacant and indicate what
that would signify with respect to these data.
2-20. Ars Technia, LLD published a news release
(Eric Bangeman, “Dell still king of market
share,” January 18, 2005) that presented the
results of a study concerning the world market
share for the major manufacturers of personal
computers. It indicated that Dell held 17.9% of
this market. The file entitled PCMarket contains
a sample of the market shares alluded to in the
article.