Question

A certain test has a population mean (mu) of 285 with a
population standard deviation (sigma) or 125. You take an SRS of
size 400 find that the sample mean (x-bar) is 288.

The sampling distribution of x-bar is approximately Normal with
mean:

The sampling distribution of x-bar is approximately Normal with
standard deviation:

Based on this sample, a 90% confidence interval for mu is:

Based on this sample, a 95% confidence interval for mu is:

Based on this sample, a 99% confidence interval for mu is:

Answer #1

To calculate the confidence intervel we will use z distribution.

A population has a mean mu=86 and a standard deviation sigma=22.
Find the mean and standard deviation of a sampling distribution of
sample means with sample size n=248.

A population has a mean mu equals 87 and a standard deviation
sigma equals 21. Find the mean and standard deviation of a sampling
distribution of sample means with sample size n equals 259.

A 90% confidence interval for mu, the population mean:
A. Always contains x-bar, the sample mean
B. Is created by a process that will yield an interval that does
not contain mu 10% of the time
C. Is wider if s, the sample standard deviation, is used than if
sigma, the population standard deviation, is known and used
D. All of the above

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2. (2 points) The sampling distribution of is
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You are given the sample mean and the population standard
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Assume the population standard deviation is
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The 90% confidence interval is
(nothing,nothing).
(Round to two decimal places as...

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The 90% confidence interval is ( , ). (Round to two decimal
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Suppose a sample of 100 size is selected and x bar is used to
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a. What is the probability that the sample mean will be within
+- 4 of the population mean (to 4 decimals)?
b. What is the probability that the sample mean will be within
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You are given the sample mean and the population standard
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