©THEBRIGHT EXAM SOLUTIONS
11/06/2024 10:41 AM
Statistics Chapter 9 Exam Questions And
Answers 100% Pass
A study of all the students at a small college showed a mean age of 20.9 and a standard
deviation of 2.9 years.
Are these numbers statistics or parameters? Explain. - answer✔The numbers are parameters
because they are for all the students, not a sample.
A study of all the students at a small college showed a mean age of 20.9 and a standard
deviation of 2.9 years.
Label both numbers with their appropriate symbol (such as x bar, μ, s, or σ). - answer✔μ=20.9
σ=2.9
A survey of 100 random full-time students at a large university showed the mean number of
semester units that students were enrolled in was 12 with a standard deviation of 1.9 units.
Are these numbers statistics or parameters? Explain. - answer✔The numbers are statistics
because they are for a sample of students, not all students.
A survey of 100 random full-time students at a large university showed the mean number of
semester units that students were enrolled in was 12 with a standard deviation of 1.9 units.
Label both numbers with their appropriate symbol (such as x bar, μ, s, or σ). - answer✔x bar=12
s=1.9
, ©THEBRIGHT EXAM SOLUTIONS
11/06/2024 10:41 AM
A biologist is studying the effects that applying insecticide to a fruit farm has on the local bat
population. She collects 23 bats and finds the mean weight of this sample to be 503.4 grams.
Assuming the selected bats are a random sample, she concludes that because the sample mean
is an unbiased estimator of the population mean, the mean weight of bats in the population is
also 503.4 grams. Explain why this is an incorrect interpretation of an unbiased estimator. -
answer✔Having an "unbiased" estimator means that the mean of the means of all possible
samples of the same size would be the same as the population mean.
Several times during the year, an organization takes random samples from the population. One
such survey, based on a large (several thousand) sample of randomly selected households,
estimates the mean retirement income to be $21,201 per year. Suppose we were to make a
histogram of all of the retirement incomes from this sample. Would the histogram be a display
of the population distribution, the distribution of a sample, or the sampling distribution of
means? - answer✔The histogram would be a display of the distribution of a sample.
A human resources manager for a large company takes a random sample of 50 employees from
the company database. She calculates the mean time that they have been employed. She
records this value and then repeats the process: She takes another random sample of 50 names
and calculates the mean employment time. After she has done this 1000 times, she makes a
histogram of the mean employment times. Is this histogram a display of the population
distribution, the distribution of a sample, or the sampling distribution of means? - answer✔The
histogram is a display of the sampling distribution of means.
The average income in a state was $56,000 per person per year. Suppose the standard
deviation is $29,000 and the distribution is right-skewed. Suppose we take a random sample of
100 residents of the state.
What value should we expect for the sample mean? Why? - answer✔The expected sample
mean is $56000, because the sample mean is an unbiased estimator of the population mean.
The average income in a state was $56,000 per person per year. Suppose the standard
deviation is $29,000 and the distribution is right-skewed. Suppose we take a random sample of
100 residents of the state.
What is the standard error for the sample mean? - answer✔The standard error for the sample
mean is $2900.
11/06/2024 10:41 AM
Statistics Chapter 9 Exam Questions And
Answers 100% Pass
A study of all the students at a small college showed a mean age of 20.9 and a standard
deviation of 2.9 years.
Are these numbers statistics or parameters? Explain. - answer✔The numbers are parameters
because they are for all the students, not a sample.
A study of all the students at a small college showed a mean age of 20.9 and a standard
deviation of 2.9 years.
Label both numbers with their appropriate symbol (such as x bar, μ, s, or σ). - answer✔μ=20.9
σ=2.9
A survey of 100 random full-time students at a large university showed the mean number of
semester units that students were enrolled in was 12 with a standard deviation of 1.9 units.
Are these numbers statistics or parameters? Explain. - answer✔The numbers are statistics
because they are for a sample of students, not all students.
A survey of 100 random full-time students at a large university showed the mean number of
semester units that students were enrolled in was 12 with a standard deviation of 1.9 units.
Label both numbers with their appropriate symbol (such as x bar, μ, s, or σ). - answer✔x bar=12
s=1.9
, ©THEBRIGHT EXAM SOLUTIONS
11/06/2024 10:41 AM
A biologist is studying the effects that applying insecticide to a fruit farm has on the local bat
population. She collects 23 bats and finds the mean weight of this sample to be 503.4 grams.
Assuming the selected bats are a random sample, she concludes that because the sample mean
is an unbiased estimator of the population mean, the mean weight of bats in the population is
also 503.4 grams. Explain why this is an incorrect interpretation of an unbiased estimator. -
answer✔Having an "unbiased" estimator means that the mean of the means of all possible
samples of the same size would be the same as the population mean.
Several times during the year, an organization takes random samples from the population. One
such survey, based on a large (several thousand) sample of randomly selected households,
estimates the mean retirement income to be $21,201 per year. Suppose we were to make a
histogram of all of the retirement incomes from this sample. Would the histogram be a display
of the population distribution, the distribution of a sample, or the sampling distribution of
means? - answer✔The histogram would be a display of the distribution of a sample.
A human resources manager for a large company takes a random sample of 50 employees from
the company database. She calculates the mean time that they have been employed. She
records this value and then repeats the process: She takes another random sample of 50 names
and calculates the mean employment time. After she has done this 1000 times, she makes a
histogram of the mean employment times. Is this histogram a display of the population
distribution, the distribution of a sample, or the sampling distribution of means? - answer✔The
histogram is a display of the sampling distribution of means.
The average income in a state was $56,000 per person per year. Suppose the standard
deviation is $29,000 and the distribution is right-skewed. Suppose we take a random sample of
100 residents of the state.
What value should we expect for the sample mean? Why? - answer✔The expected sample
mean is $56000, because the sample mean is an unbiased estimator of the population mean.
The average income in a state was $56,000 per person per year. Suppose the standard
deviation is $29,000 and the distribution is right-skewed. Suppose we take a random sample of
100 residents of the state.
What is the standard error for the sample mean? - answer✔The standard error for the sample
mean is $2900.
