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 23.1 ho There is a known population standard deviation of 6.2 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.) O Part (a) Find the following. (Enter exact numbers as integers, fractions, or decimals.) (i) (ii) (ii) n = O Part (b) O Part (c) Which distribution should you use for this problem? (Round your answers to two decimal places.) X- ? v Explain your choice. O The Student's t-distribution should be used because the sample standard deviation is given. O The standard normal distribution should be used because the mean is given. O The Student's t-distribution should be used because the sample mean is smaller than 30. O The standard normal distribution should be used because the population standard deviation is known. Correct! To be able to use the standard normal distribution, the standard deviation of the population must be know. O Part (d)

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O S.I.A. Best Songs V x
O Syllabus for Statistics
* Hmwk: Chapter 8 - Mat x
My Questions | bartleb
= 6.1 The Standard Norm x
Bookmarks
+
A webassign.net/web/Student/Assignment-Responses/last?dep=25262768
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 23.1 hours.
There is a known population standard deviation of 6.2 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.)
O Part (a)
Find the following. (Enter exact numbers as integers, fractions, or decimals.)
(i) x=
(ii)
(ii)
n =
O Part (b)
O Part (c)
Which distribution should you use for this problem? (Round your answers to two decimal places.)
X- ? v
Explain your choice.
O The Student's t-distribution should be used because the sample standard deviation is given.
The standard normal distribution should be used because the mean is given.
O The Student's t-distribution should be used because the sample mean is smaller than 30.
The standard normal distribution should be used because the population standard deviation is known.
Correct! To be able to use the standard normal distribution, the standard deviation of the population must be know.
O Part (d)
Transcribed Image Text:O S.I.A. Best Songs V x O Syllabus for Statistics * Hmwk: Chapter 8 - Mat x My Questions | bartleb = 6.1 The Standard Norm x Bookmarks + A webassign.net/web/Student/Assignment-Responses/last?dep=25262768 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 23.1 hours. There is a known population standard deviation of 6.2 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.) O Part (a) Find the following. (Enter exact numbers as integers, fractions, or decimals.) (i) x= (ii) (ii) n = O Part (b) O Part (c) Which distribution should you use for this problem? (Round your answers to two decimal places.) X- ? v Explain your choice. O The Student's t-distribution should be used because the sample standard deviation is given. The standard normal distribution should be used because the mean is given. O The Student's t-distribution should be used because the sample mean is smaller than 30. The standard normal distribution should be used because the population standard deviation is known. Correct! To be able to use the standard normal distribution, the standard deviation of the population must be know. O Part (d)
O S.I.A. Best Songs V x
O Syllabus for Statistics
* Hmwk: Chapter 8 - Mat x
My Questions | bartleby x
= 6.1 The Standard Norm x
Bookmarks
A webassign.net/web/Student/Assignment-Responses/last?dep=25262768
Correct! To be able to use the standard normal distribution, the standard deviation of the population must be know.
O Part (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.)
a
a
C.L. =
%3D
(iii) Calculate the error bound. (Round your answer to two decimal places.)
O Part (e)
+ Part (f)
O Part (g)
Additional Materials
Transcribed Image Text:O S.I.A. Best Songs V x O Syllabus for Statistics * Hmwk: Chapter 8 - Mat x My Questions | bartleby x = 6.1 The Standard Norm x Bookmarks A webassign.net/web/Student/Assignment-Responses/last?dep=25262768 Correct! To be able to use the standard normal distribution, the standard deviation of the population must be know. O Part (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.) a a C.L. = %3D (iii) Calculate the error bound. (Round your answer to two decimal places.) O Part (e) + Part (f) O Part (g) Additional Materials
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