Question

A random sample of 64 observations produced a mean value of 73 and standard deviation of 6.5. The 90% confidence interval for the population mean μ is between?

a) 69.663 and 76.337

b) 71.408 and 74.593

c) 71.663 and 74.337

d) 71.163 and 74.837

e) 72.163 and 73.837

Answer #1

(1 pt) A random sample of 100 observations produced a mean of
x-bar = 23.1 from a population with a normal distribution and a
standard deviation = 2.42. (a) Find a 90% confidence interval (b)
Find a 99% confidence interval (c) Find a 95% confidence
interval

A statistics practitioner took a random sample of 56
observations from a population whose standard deviation is 32 and
computed the sample mean to be 102.
Note: For each confidence interval, enter your answer in the
form (LCL, UCL). You must include the parentheses and the comma
between the confidence limits.
A. Estimate the population mean with 95% confidence.
Confidence Interval =
B. Estimate the population mean with 90% confidence.
Confidence Interval = C.
Estimate the population mean with 99%...

A statistics practitioner took a random sample of 40
observations from a population whose standard deviation is 15 and
compute the sample mean to be 50. The 90% confidence interval for
the mean will be between __________ and __________.

A statistics practitioner took a random sample of 56
observations from a population whose standard deviation is 29 and
computed the sample mean to be 97. Note: For each confidence
interval, enter your answer in the form (LCL, UCL). You must
include the parentheses and the comma between the confidence
limits.
A. Estimate the population mean with 95% confidence. Confidence
Interval =
B. Estimate the population mean with 95% confidence, changing
the population standard deviation to 58; Confidence Interval =...

A statistics practitioner took a random sample of 57
observations from a population whose standard deviation is 29 and
computed the sample mean to be 97.
Note: For each confidence interval, enter your
answer in the form (LCL, UCL). You must include the parentheses and
the comma between the confidence limits.
A. Estimate the population mean with 95% confidence.
Confidence Interval =
B. Estimate the population mean with 95% confidence, changing
the population standard deviation to 48;
Confidence Interval =...

1. Consider a normally
distributed population with a standard deviation of 64. If a random
sample of 90 from the population produces a sample mean of 250,
construct a 95% confidence interval for the true mean of the
population.
2.A psychologist is
studying learning in rats (to run a maze). She has a sample of 40
rats and their mean time to run the maze if 5 minutes with a
standard deviation of 1. Estimate the average time to run...

A sample of 23 observations is selected from a normal population
where the sample standard deviation is 4.95. The sample mean is
16.90.
a. Determine the standard error of the mean.
(Round the final answer to 2 decimal places.)
The standard error of the mean is _______ .
b. Determine the 90% confidence interval for
the population mean. (Round the t-value to 3
decimal places. Round the final answers to 3 decimal
places.)
The 90% confidence interval for the population...

A random sample of 20 observations is used to estimate the
population mean. The sample mean and the sample standard deviation
are calculated as 152 and 74, respectively. Assume that the
population is normally distributed.
What is the margin of error for a 95% confidence interval for
the population mean?
Construct the 95% confidence interval for the population
mean.
Construct the 90% confidence interval for the population
mean.
Construct the 78% confidence interval for the population mean.
Hint: Use Excel...

A statistics practitioner took a random sample of 80
observations from a population with a standard deviation of 25 and
compute the sample mean to be 100.
(a) Estimate the population mean confidence interval with 90%
confidence level, 95% confidence level and 99% confidence
level.
(b) Describe the effect of increasing the confidence level on
the confidence interval.
(c) At 99% confidence level, if the population standard
deviation is reduced to 16, will the confidence interval be wider
or narrower?

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.

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