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Introductory Statistics

Douglas Shafer

Chapter 1

Introduction - all with Video Answers

Educators

Section 1

Basic Definitions and Concepts

01:57

Problem 1

Explain what is meant by the term population.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:31

Problem 2

Explain what is meant by the term sample.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:07

Problem 3

Explain how a sample differs from a population.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:14

Problem 4

Explain what is meant by the term sample data.

Harsh Gadhiya
Harsh Gadhiya
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01:32

Problem 5

Explain what a parameter is.

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Harsh Gadhiya
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01:08

Problem 6

Explain what a statistic is.

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Harsh Gadhiya
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01:22

Problem 7

Give an example of a population and two different characteristics that may be of interest.

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Harsh Gadhiya
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01:41

Problem 8

Describe the difference between descriptive statistics and inferential statistics. Illustrate with an example.

Harsh Gadhiya
Harsh Gadhiya
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01:29

Problem 9

Identify each of the following data sets as either a population or a sample:
a. The grade point averages (GPAs) of all students at a college.
b. The GPAs of a randomly selected group of students on a college campus.
C. The ages of the nine Supreme Court Justices of the United States on January 1, 1842 .
d. The gender of every second customer who enters a movie theater.
e. The lengths of Atlantic croakers caught on a fishing trip to the beach.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:38

Problem 10

Identify the following measures as either quantitative or qualitative:
a. The 30 high-temperature readings of the last 30 days.
b. The scores of 40 students on an English test.
c. The blood types of 120 teachers in a middle school.
d. The last four digits of social security numbers of all students in a class.
e. The numbers on the jerseys of 53 football players on a team.

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Harsh Gadhiya
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01:07

Problem 11

Identify the following measures as either quantitative or qualitative:
a. The genders of the first 40 newborns in a hospital one year.
b. The natural hair color of 20 randomly selected fashion models.
c. The ages of 20 randomly selected fashion models.
d. The fuel economy in miles per gallon of 20 new cars purchased last month.
e. The political affiliation of 500 randomly selected voters.

Harsh Gadhiya
Harsh Gadhiya
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02:01

Problem 12

A researcher wishes to estimate the average amount spent per person by visitors to a theme park. He takes a
random sample of forty visitors and obtains an average of $\$ 28$ per person.
a. What is the population of interest?
b. What is the parameter of interest?
c. Based on this sample, do we know the average amount spent per person by visitors to the park?
Explain fully.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:36

Problem 13

A researcher wishes to estimate the average weight of newborns in South America in the last five years. He takes a random sample of 235 newborns and obtains an average of 3.27 kilograms.
a. What is the population of interest?
b. What is the parameter of interest?
c. Based on this sample, do we know the average weight of newborns in South America? Explain fully.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
02:10

Problem 14

A researcher wishes to estimate the proportion of all adults who own a cell phone. He takes a random
sample of 1,572 adults; 1,298 of them own a cell phone, hence $1298 / 1572 \approx .83$ or about $83 \%$ own a cell
phone.
a. What is the population of interest?
b. What is the parameter of interest?
c. What is the statistic involved?
d. Based on this sample, do we know the proportion of all adults who own a cell phone? Explain fully.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:54

Problem 15

A sociologist wishes to estimate the proportion of all adults in a certain region who have never married. In a
random sample of 1,320 adults, 145 have never married, hence $145 / 1320 \approx .11$ or about $11 \%$ have never
married.
a. What is the population of interest?
b. What is the parameter of interest?
c. What is the statistic involved?
d. Based on this sample, do we know the proportion of all adults who have never married? Explain fully.

Harsh Gadhiya
Harsh Gadhiya
Numerade Educator
01:37

Problem 16

a. What must be true of a sample if it is to give a reliable estimate of the value of a particular
population parameter?
b. What must be true of a sample if it is to give certain knowledge of the value of a particular
population parameter?

Emily Himsel
Emily Himsel
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