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Stats FINAL Exam | Questions And Answers Latest {} A+ Graded | 100% Verified
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Stats FINAL Exam | Questions And Answers Latest {2024- 2025} A+ Graded | 100%Verified
When determining the sample size for a proportion for a given level of confidence and sampling error,
the closer to 0.50 that π is estimated to be, the sample size required ________. - larger
The width of a confidence interval estimate for a proportion will be - narrower for 90% confidence than
for 95% confidence.
A 99% confidence interval estimate can be interpreted to mean that - both of the above
If you were constructing a 99% confidence interval of the population mean based on a sample of n = 25,
where the standard deviation of the sample s = 0.05, the critical value of t will be - 2.7970.
Which of the following is NOT true about the Student's t distribution? - It is used to construct confidence
intervals for the population mean when the population standard deviation is known.
Suppose a 95% confidence interval for μ turns out to be (1,000, 2,100). Give a definition of what it
means to be "95% confident" as an inference. - In repeated sampling, 95% of the intervals constructed
would contain the population mean.
Suppose a 95% confidence interval for has been constructed. If it is decided to take a larger sample and
to decrease the confidence level of the interval, then the resulting interval width would . (Assume that
the sample statistics gathered would not change very much for the new sample.) - be narrower than the
current interval width
In the construction of confidence intervals, if all other quantities are unchanged, an increase in the
sample size will lead to an interval that's.. - narrower
A major department store chain is interested in estimating the average amount its credit card customers
spent on their first visit to the chain's new store in the mall. Fifteen credit card accounts were randomly
sampled and analyzed with the following results: X = $50.50 and s 2 = 400 . Assuming the distribution of
the amount spent on their first visit is approximately normal, what is the shape of the sampling
,distribution of the sample mean that will be used to create the desired confidence interval for - A t
distribution with 14 degrees of freedom
A major department store chain is interested in estimating the average amount its credit card customers
spent on their first visit to the chain's new store in the mall. Fifteen credit card accounts were randomly
sampled and analyzed with the following results: $50.50 X = and s 2 = 400 . Construct a 95% confidence
interval for the average amount its credit card customers spent on their first visit to the chain's new
store in the mall assuming that the amount spent follows a normal distribution - $50.50 +- $11.08
Private colleges and universities rely on money contributed by individuals and corporations for their
operating expenses. Much of this money is put into a fund called an endowment, and the college spends
only the interest earned by the fund. A recent survey of 8 private colleges in the United States revealed
the following endowments (in millions of dollars): 60.2, 47.0, 235.1, 490.0, 122.6, 177.5, 95.4, and 220.0.
What value will be used as the point estimate for the mean endowment of all private colleges in the
United States? - $180.975
Private colleges and universities rely on money contributed by individuals and corporations for their
operating expenses. Much of this money is put into a fund called an endowment, and the college spends
only the interest earned by the fund. A recent survey of 8 private colleges in the United States revealed
the following endowments (in millions of dollars): 60.2, 47.0, 235.1, 490.0, 122.6, 177.5, 95.4, and 220.0.
Summary statistics yield X = 180.975 and s = 143.042 . Calculate a 95% confidence interval for the mean
endowment of all the private colleges in the United States assuming a normal distribution for the
endowments - $180.975 ± $119.586
A university system enrolling hundreds of thousands of students is considering a change in the way
students pay for their education. Currently, the students pay $55 per credit hour. The university system
administrators are contemplating charging each student a set fee of $750 per quarter, regardless of how
many credit hours each takes. To see if this proposal would be economically feasible, the administrators
would like to know how many credit hours, on the average, each student takes per quarter. A random
sample of 250 students yields a mean of 14.1 credit hours per quarter and a standard deviation of 2.3
credit hours per quarter. Suppose the administration wanted to estimate the mean to within 0.1 hours
at 95% reliability and assumed that the sample standard deviation provided a good estimate for the
population standard deviation. How large a total sample would they need to take? - n = 2033
As an aid to the establishment of personnel requirements, the director of a hospital wishes to estimate
the mean number of people who are admitted to the emergency room during a 24-hour period. The
director randomly selects 64 different 24-hour periods and determines the number of admissions for
each. For this sample, X = 19.8 and s 2 = 25. Estimate the mean number of admissions per 24-hour
period with a 95% confidence interval - 19.8 ± 1.249
, As an aid to the establishment of personnel requirements, the director of a hospital wishes to estimate
the mean number of people who are admitted to the emergency room during a 24-hour period. The
director randomly selects 64 different 24-hour periods and determines the number of admissions for
each. For this sample, X = 19.8 and s 2 = 25. If the director wishes to estimate the mean number of
admissions per 24-hour period to within 1 admission with 99% reliability, what size sample should she
choose? - n = 166
A university dean is interested in determining the proportion of students who receive some sort of
financial aid. Rather than examine the records for all students, the dean randomly selects 200 students
and finds that 118 of them are receiving financial aid. Use a 90% confidence interval to estimate the true
proportion of students who receive financial aid - 0.59 ± 0.057 or 0.533 ≤ (Pie symbol) ≤ 0.647
A university dean is interested in determining the proportion of students who receive some sort of
financial aid. Rather than examine the records for all students, the dean randomly selects 200 students
and finds that 118 of them are receiving financial aid. The 95% confidence interval for (pie symbol) is
0.59 ± 0.07. Interpret this interval - We are 95% confident that the true proportion of all students
receiving financial aid is between 0.52 and 0.66.
A university dean is interested in determining the proportion of students who receive some sort of
financial aid. Rather than examine the records for all students, the dean randomly selects 200 students
and finds that 118 of them are receiving financial aid. If the dean wanted to estimate the proportion of
all students receiving financial aid within 3% with 99% reliability, how many students would need to be
sampled? - n = 1,784
An economist is interested in studying the incomes of consumers in a particular region. The population
standard deviation is known to be $1,000. A random sample of 50 individuals resulted in an average
income of $15,000. What is the upper end point in a 99% confidence interval for the average income? -
$15,364
An economist is interested in studying the incomes of consumers in a particular region. The population
standard deviation is known to be $1,000. A random sample of 50 individuals resulted in an average
income of $15,000. What is the width of the 90% confidence interval? - $465.23
An economist is interested in studying the incomes of consumers in a particular region. The population
standard deviation is known to be $1,000. A random sample of 50 individuals resulted in an average
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