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114 CHAPTER 2 • Modeling One-Variable Quantitative Data

LESSON APP 2.3 Answers LESSON APP 2 . 3
1. Still waiting for the server?
1
Height =
3600 How does your web browser get a file from the
Internet? Your computer sends a request for the file
0 3600
Time (sec) to a web server, and the web server sends back a
response. For one particular web server, the time (in
300
2. = 0.083 seconds) after the start of an hour at which a ran-
3600 domly selected request is received can be modeled
=
3. Q 3 = (0.75)(3600) 2700 seconds; by a uniform distribution on the interval from 0 to
3600 seconds.
=
Q 1 = (0.25)(3600)900 seconds; Masson/Shutterstock
(C) 2021 BFW Publishers -- for review purposes only.

=
IQR = 2700–900 1800 seconds 1. Draw a density curve to model the amount of
time after an hour at which a request is received
=
=
4. mean 3600/2 1800 seconds by the web server. Be sure to include scales on 3. Find the interquartile range of this distribution.

(balance point) both axes. 4. What is the mean of the density curve? Explain

=
5. median 1800 seconds (equal-areas 2. About what proportion of requests are received your answer.
within the first 5 minutes (300 seconds) after
What is the median of the density curve? Explain
point) the hour? 5. What is the median of the density curve? Explain
your answer.
LESSON 2.1 2.3 QUIZ
You can find a prepared quiz for Lesson 2.3
Lessons 2.1–2.3 by clicking on the
link in the TE-book or by logging into WHA T DID Y OU LEARN ?
the teachers’ resources on our digital LEARNING TARGET EXAMPLES EXERCISES
platform. Use a density curve to model a distribution of quantitative data. p. 109 7–10
Identify the relative locations of the mean and median of a p. 111 11–14
FULL SOLUTIONS TO LESSON 2.3 distribution from a density curve.
EXERCISES Draw a normal curve to model a distribution of quantitative data. p. 113 15–18
You can find the full solutions for this
lesson by clicking on the link in the
TE-book or by logging into the teachers’ Exercises Lesson 3.1
resources on our digital platform.
Building Concepts and Skills 4. The of a density curve is its balance
Answers to Lesson 2.3 Exercises 1. In this lesson, we added one more step to our strat- point. The of a density curve is the

equal-areas point.
egy of describing distributions of quantitative data:

1. overall pattern When there’s a regular , use a sim- 5. True/False: For a left-skewed density curve, the
mean will be greater than the median.

plified model called a density curve to describe it.
2. True 2. True/False: The area under a density curve and above 6. True/False: The standard deviation of a normal distri-
an interval of values on the horizontal axis estimates the bution is half the distance between the mean and the
3. False. A density curve is an idealized proportion of all observations that fall in that interval. maximum.
model for a distribution of quantitative 3. True/False: A density curve is an exact model for a

data. distribution of quantitative data
4. mean; median
5. False. For a left-skewed density curve,
the mean will be less than the median.
6. False. The standard deviation on
a normal curve can be estimated by 03_StarnesSPA4e_24432_ch02_088_153.indd 114 07/09/20 1:55 PM
noticing the point at which the change
in curvature occurs.

114 CHAPTER 2 • Modeling One-Variable Quantitative Data

03_TysonTEspa4e_25177_ch02_088_153_4pp.indd 114 10/11/20 7:45 PM