Statistics Chapter 9 Exam Questions and Answers Latest Update 2024 Already Passed
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. - Answers The numbers are parameters because th...
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. - Answers 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). - Answers 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. - Answers 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). - Answers x bar=12
s=1.9
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. - Answers 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? - Answers 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? - Answers 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? - Answers 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? - Answers The standard error for the sample mean is
$2900.
The average income in a state was $43,000 per person per year. Suppose the standard deviation is
$31,000 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? - Answers The expected sample mean is
$43000, because the sample mean is an unbiased estimator of the population mean.
The average income in a state was $43,000 per person per year. Suppose the standard deviation is
$31,000 and the distribution is right-skewed. Suppose we take a random sample of 100 residents of the
state.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller TutorJosh. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.99. You're not tied to anything after your purchase.
