Question

**PROBLEM: Suppose that an accounting firm does a study to
determine the time needed to complete one person's tax forms. It
randomly surveys 200 people. The sample mean is 23.1 hours. There
is a known population standard deviation of 6.2 hours. The
population distribution is assumed to be normal.**

**a) Find the following. (Enter exact numbers as integers,
fractions, or decimals.)**

x-bar = ______

σ = ______

n = _______

**b) In words, define the random variables X and
X-bar**

X-bar is the time needed to complete one person's tax forms, and
*X* is the mean time needed to complete tax forms from a
sample of 200 customers.

*X* is the number of tax forms that an accounting firm
completes, and X-bar is the mean number of tax forms that an
accounting firm completes.

*X* is the time needed to complete one person's tax
forms, and X-bar is the mean time needed to complete tax forms from
a sample of 200 customers.

X-bar is the number of tax forms that an accounting firm
completes, and *X* is the mean number of tax forms that an
accounting firm completes.

**c) Which distribution should you use for this problem?
(Round your answers to two decimal places.)**

X-bar ~ ____ (___,___)

Explain your choice.

The standard normal distribution should be used because the mean is given.

The standard normal distribution should be used because the population standard deviation is known.

The Student's *t*-distribution should be used because the
sample standard deviation is given.

The Student's *t*-distribution should be used because the
sample mean is smaller than 30.

**d) Construct a 90% confidence interval for the
population mean time to complete the tax forms.**

(i) State the confidence interval. (Round your answers to two decimal places.)

(____,____)

(ii) Sketch the graph. (Round your answers to two decimal places.)

^ ____ ^____

(iii) Calculate the error bound. (Round your answer to two decimal places.)

Answer #1

a)

b)

*X* is the time needed to complete one person's tax
forms, and X-bar is the mean time needed to complete tax forms from
a sample of 200 customers.

c)

We have

So,

The standard normal distribution should be used because the population standard deviation is known.

d)

(i)

(ii)

(iii)

------------------------------------------

Suppose that an accounting firm does a study to determine the
time needed to complete one person's tax forms. It randomly surveys
175 people. The sample mean is 22.1 hours. There is a known
population standard deviation of 6.6 hours. The population
distribution is assumed to be normal.
NOTE: If you are using a Student's t-distribution, you may
assume that the underlying population is normally distributed. (In
general, you must first prove that assumption, though.)
A. Find the following. (Enter exact...

Suppose that an accounting firm does a study to determine the
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Construct a 90% confidence interval for the population mean time
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(iii) Calculate the error bound. (Round your answer to two
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I don't understand the error...

supposed in accounting firm does a study to determine the time
needed to complete one persons tax forms it randomly surveys 80
people the sample mean is 30.2 hours there is a known standard
deviation of 8.0 hours the population distribution is assumed to be
normal construct a 99% confidence interval for the population mean
time to complete the tax forms.
Sample mean
Error bound Margin
Population Standard Deviation
Confidence level
Lower and Upper Bound

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population standard deviation of 7.0 hours. The population
distribution is assumed to be normal.
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interval.
B. Find and interpret the 95% confidence interval for the mean
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QUESTION 25
Suppose professor finds that for 16 randomly selected students
the time needed to complete an assignment had a sample mean of 65
minutes and a sample standard deviation of 40 minutes. The 98%
confidence interval estimate for the population
mean is:
QUESTION 26
After estimating the interval in the previous question, we can
interpret it as:
a.
We are 98% confident that the sample mean falls into the
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b.
We are 98% confident that the estimated...

A professor finds that for 16 randomly selected students the
time needed to complete an assignment had a sample mean of 64
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standard error of the mean is
a.
20
b.
16
c.
5
d.
4
QUESTION 24
A professor finds that for 16 randomly selected students the
time needed to complete an assignment had a sample mean...

An organization installs new garage doors on residential homes.
Suppose the installation time for a residence follows the uniform
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a. What is the probability that an installation will require
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The probability is ________.
(Round to four decimal places as needed.)
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An automobile dealer conducted a test to determine if the time
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Analyzer
Computerized
Electronic
Car
Compact
50
41
Intermediate
54
44
Full-sized
64
47
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