1.13 Sampling and data: homework (edited: teegarden)  (Page 3/3)

Nineteen immigrants to the U.S were asked how many years, to the nearest year, they have lived in the U.S. The data are as follows:

• 2
• 5
• 7
• 2
• 2
• 10
• 20
• 15
• 0
• 7
• 0
• 20
• 5
• 12
• 15
• 12
• 4
• 5
• 10

The following table was produced:

• A

  Fix the errors on the table. Also, explain how someone might have arrived at the incorrect number(s).

• B

  Explain what is wrong with this statement: “47 percent of the people surveyed have lived in the U.S. for 5 years.”

• C

  Fix the statement above to make it correct.

• D

  What fraction of the people surveyed have lived in the U.S. 5 or 7 years?

• E

  What fraction of the people surveyed have lived in the U.S. at most 12 years?

• F

  What fraction of the people surveyed have lived in the U.S. fewer than 12 years?

• G

  What fraction of the people surveyed have lived in the U.S. from 5 to 20 years, inclusive?

A “random survey” was conducted of 3274 people of the “microprocessor generation” (people born since 1971, the year the microprocessor was invented). It was reported that 48% of those individuals surveyed stated that if they had $2000 to spend, they would use it for computer equipment. Also, 66% of those surveyed considered themselves relatively savvy computer users. ( Source: San Jose Mercury News )

• A

  Do you consider the sample size large enough for a study of this type? Why or why not?

• B

  Based on your “gut feeling,” do you believe the percents accurately reflect the U.S. population for those individuals born since 1971? If not, do you think the percents of the population are actually higher or lower than the sample statistics? Why?

Additional information: The survey was reported by Intel Corporation of individuals who visited the Los Angeles Convention Center to see the Smithsonian Institure's road show called “America’s Smithsonian.”

• C

  With this additional information, do you feel that all demographic and ethnic groups were equally represented at the event? Why or why not?

• D

  With the additional information, comment on how accurately you think the sample statistics reflect the population parameters.

• A

  List some practical difficulties involved in getting accurate results from a telephone survey.

• B

  List some practical difficulties involved in getting accurate results from a mailed survey.

• C

  With your classmates, brainstorm some ways to overcome these problems if you needed to conduct a phone or mail survey.

What is the population she is interested in?

• A

  All Lake Tahoe Community College students

• B

  All Lake Tahoe Community College English students

• C

  All Lake Tahoe Community College students in her classes

• D

  All Lake Tahoe Community College math students

Consider the following:

$X$ = number of days a Lake Tahoe Community College math student is absent

In this case, $X$ is an example of a:

• A

  Variable

• B

  Population

• C

  Statistic

• D

  Data

The instructor takes her sample by gathering data on 5 randomly selected students from each Lake Tahoe Community College math class. The type of sampling she used is

• A

  Cluster sampling

• B

  Stratified sampling

• C

  Simple random sampling

• D

  Convenience sampling

The instructor’s sample produces an average number of days absent of 3.5 days. This value is an example of a

• A

  Parameter

• B

  Data

• C

  Statistic

• D

  Variable

What is the relative frequency of direct hits were category 4 hurricanes?

• A

  0.0768

• B

  0.0659

• C

  0.2601

• D

  Not enough information to calculate

What is the relative frequency of direct hits were AT MOST a category 3 storm?

• A

  0.3480

• B

  0.9231

• C

  0.2601

• D

  0.3370

‘Number of times per week’

• A

  qualitative

• B

  quantitative - discrete

• C

  quantitative - continuous

The sampling method was:

• A

  simple random

• B

  systematic

• C

  stratified

• D

  cluster

‘Duration (amount of time)’

• A

  qualitative

• B

  quantitative - discrete

• C

  quantitative - continuous