STA Quiz Questions Exam 1 || correct answers 100%.
Descriptive statistics refers to methods of making decisions or predictions about a population,
based on data obtained from a sample of that population; while inferential statistics refers to
methods for summarizing the data. correct answers False
The job placement center at your school surveys all graduating seniors at the school. Their report
about the survey provides numerical summaries such as the average starting salary and the
percentage of students earning more than $35,000 a year.
a. Are these descriptive, or inferential, statistical analyses? Explain.
b. Are these numerical summaries better characterized as statistics or as parameters? correct
answers a. Descriptive, because they summarize the data collected.
b. Parameters, because the analyses summarize data on a population.
You are about to take the road test for your driver's license. You hear that only 31% of candidates
pass the test the first time, but the percentage rises to 79% on subsequent retests. Estimate the
average number of tests drivers take in order to get a license. Your
simulation should use at least 20 runs. correct answers 1.9
A historian wants to estimate the average age at marriage of menmen in a region in the early 19th
century. Within herher state's archives, she finds marriage records for the years 1800-1820,
which she treats as a sample of all marriage records from the early 19th century. The average age
of the men in the records is 29.4 years. Using the appropriate statistical method, she estimates
that the average age of grooms in the region in the early 19th century was between 28.7 and 30.1
years.
a. Which part of this example gives a descriptive summary of the data?
b. Which part of this example draws an inference about a population?
c. To what population does the inference in part b refer?
d. The average age of the sample was 29.4 years. Is 29.4 a statistic or a parameter? correct
answers a. The average age 29.4 years
, b. The interval of ages between 28.7 and 30.1 years
c. the men in the region in the early 19th century
d. statistic
To estimate the percentage of defective items a machine is producing, a quality control analyst
inspects the first 100 items produced in a day. This technique produces a random sample. correct
answers false
A study attempted to estimate the proportion of Florida residents who were willing to spend
more tax dollars on protecting the Florida beaches from environmental disasters. Twenty-four
hundred Florida residents were surveyed. Which of the following is the population of interest in
the study? correct answers all Florida residents
A manufacturer of cellular phones has decided that an assembly line is operating satisfactorily if
less than 6% of the phones manufactured per day are defective. To check the quality of a day's
production, the company decides to randomly sample 30 phones from a day's production and test
for defects. Define the sample of interest to the manufacturer. correct answers the 30 cellular
phones that were sampled and tested
Planning the methods for data collection to study the effects of Vitamin E on athletic strength
would be classified as which aspect of statistics: design, inference, or description? correct
answers design
dentify each of the following variables as continuous or discrete.
a. The length of time to run a marathonThe length of time to run a marathon
b. The number of socks in a drawerThe number of socks in a drawer
c. The number of people in line at a box office to purchase theater ticketsThe number of people
in line at a box office to purchase theater tickets
d. The time spent in line for a rollercoaster correct answers a. The length of time to run a
marathon is a continuous variable since it has an infinite continuuman infinite continuum of
possible values.
Descriptive statistics refers to methods of making decisions or predictions about a population,
based on data obtained from a sample of that population; while inferential statistics refers to
methods for summarizing the data. correct answers False
The job placement center at your school surveys all graduating seniors at the school. Their report
about the survey provides numerical summaries such as the average starting salary and the
percentage of students earning more than $35,000 a year.
a. Are these descriptive, or inferential, statistical analyses? Explain.
b. Are these numerical summaries better characterized as statistics or as parameters? correct
answers a. Descriptive, because they summarize the data collected.
b. Parameters, because the analyses summarize data on a population.
You are about to take the road test for your driver's license. You hear that only 31% of candidates
pass the test the first time, but the percentage rises to 79% on subsequent retests. Estimate the
average number of tests drivers take in order to get a license. Your
simulation should use at least 20 runs. correct answers 1.9
A historian wants to estimate the average age at marriage of menmen in a region in the early 19th
century. Within herher state's archives, she finds marriage records for the years 1800-1820,
which she treats as a sample of all marriage records from the early 19th century. The average age
of the men in the records is 29.4 years. Using the appropriate statistical method, she estimates
that the average age of grooms in the region in the early 19th century was between 28.7 and 30.1
years.
a. Which part of this example gives a descriptive summary of the data?
b. Which part of this example draws an inference about a population?
c. To what population does the inference in part b refer?
d. The average age of the sample was 29.4 years. Is 29.4 a statistic or a parameter? correct
answers a. The average age 29.4 years
, b. The interval of ages between 28.7 and 30.1 years
c. the men in the region in the early 19th century
d. statistic
To estimate the percentage of defective items a machine is producing, a quality control analyst
inspects the first 100 items produced in a day. This technique produces a random sample. correct
answers false
A study attempted to estimate the proportion of Florida residents who were willing to spend
more tax dollars on protecting the Florida beaches from environmental disasters. Twenty-four
hundred Florida residents were surveyed. Which of the following is the population of interest in
the study? correct answers all Florida residents
A manufacturer of cellular phones has decided that an assembly line is operating satisfactorily if
less than 6% of the phones manufactured per day are defective. To check the quality of a day's
production, the company decides to randomly sample 30 phones from a day's production and test
for defects. Define the sample of interest to the manufacturer. correct answers the 30 cellular
phones that were sampled and tested
Planning the methods for data collection to study the effects of Vitamin E on athletic strength
would be classified as which aspect of statistics: design, inference, or description? correct
answers design
dentify each of the following variables as continuous or discrete.
a. The length of time to run a marathonThe length of time to run a marathon
b. The number of socks in a drawerThe number of socks in a drawer
c. The number of people in line at a box office to purchase theater ticketsThe number of people
in line at a box office to purchase theater tickets
d. The time spent in line for a rollercoaster correct answers a. The length of time to run a
marathon is a continuous variable since it has an infinite continuuman infinite continuum of
possible values.
