Question

The HR Department wants to estimate the interval for the population mean number of absences in a quarter for the agency’s employees using the following data at the 95 percent level of confidence. Number of absences (in days) for a random sample of 10 employees 0 1 1 2 2 2 3 4 6 9

Answer #1

A researcher wants to estimate the mean number of novels that
seniors read during their time at her university. An exit survey
was conducted with a random sample of 11 seniors. The results are
shown below. The sample mean was 9 novels with a standard deviation
of 2.366 novels.
Number of Novels 5 6 7 9 9 9 9 10 10 12 13
(a) Sketch a dot plot of the sample data. Describe the
distribution of sample data.
(b) Construct...

In order to estimate the annual cost of full time-employees
absences full time employees take per year. Based on previous
studies, it's assumed s= 2.1 days.
a) How big a sample must be selected if the company wants to be
90% confident that their estimate is within 1 day of the true
mean?
b) Repeat (a) using a 95% confidence interval.
c) Which level of confidence requires a larger sample size?
Explain.

Think about a population mean that you may be interested in and
propose a confidence interval problem for this parameter. Your data
values should be approximately normal.
For example, you may want to estimate the population mean number
of times that adults go out for dinner each week. Your data could
be that you spoke with seven people you know and found that they
went out 1, 4, 2, 3, 2, 0, and 5 times last week. You then would...

An animal shelter wants to estimate the mean number of animals
housed daily. A sample of 30 days resulted in a standard deviation
of 4.2 animals. If they want to find a 95 percent confidence
interval, what is the margin of error for the number of animals
housed daily?
1.661
1.503
1.568
0.829

A researcher wishes to estimate the number of days it takes an
automobile dealer to sell a Ferrari 458. A random sample of 50 cars
had a mean time on the dealer’s lot of 54 days. Assume the
population standard deviation to be 6.0 days.
1. Find the best point estimate of the population mean.
DAYS. (Round answer to two decimal places)
2. Find the margin of error for the 95% confidence level.
DAYS. (Round answer to two decimal places)...

A department store manager wants to estimate with a 99%
confidence interval the mean amount spent by all customers at the
store. How large of a sample should be taken if the manager is
willing to tolerate an error of $3. Assume the population standard
deviation is $31.

4. What is the minimum sample size to select to find the mean
number of absences per month for school children, within ±0.2
points at a 95 % Confidence Level if it is known that the standard
deviation is 1.1 days?

A random sample of 24 observations is used to estimate the
population mean. The sample mean and the sample standard deviation
are calculated as 104.6 and 28.8,
respectively. Assume that the population is normally
distributed. Construct the 90% confidence interval for the
population mean. Then, construct the 95% confidence
interval for the population mean. Finally, use your answers to
discuss the impact of the confidence level on the width of the
interval.

You are interested in finding a 95% confidence interval for the
average number of days of class that college students miss each
year. The data below show the number of missed days for 12 randomly
selected college students.
3
12
8
1
10
10
6
1
7
7
4
9
a. To compute the confidence interval use a distribution.
b. With 95% confidence the population mean number of days of
class that college students miss is between answer _____ and...

Consider a population having a standard deviation equal to 9.94.
We wish to estimate the mean of this population.
(a) How large a random sample is needed to
construct a 95% confidence interval for the mean of this population
with a margin of error equal to 1? (Round your answer to
the next whole number.)
The random sample is
units.
(b) Suppose that we now take a random sample of
the size we have determined in part a. If we...

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