Question
In: Statistics and Probability
A simple random sample of 60 items resulted in a sample mean of 80. The population...
A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is
σ = 5.
(a)
Compute the 95% confidence interval for the population mean. (Round your answers to two decimal places.)
to
(b)
Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence interval for the population mean. (Round your answers to two decimal places.)
to
Solutions
Expert Solution
a)
95% confidence interval for 
is
- Z *
/ sqrt(n) <
< + Z *
/ sqrt(n)
80 - 1.96 * 5 / sqrt(60) < < 80 + 1.96 * 5
/ sqrt(60)
78.73 < < 81.27
95% CI is ( 78.73 to 81.27 )
b)
95% confidence interval for is
- Z *
/ sqrt(n) <
< + Z *
/ sqrt(n)
80 - 1.96 * 5 / sqrt(120) < < 80 + 1.96 * 5
/ sqrt(120)
79.11 < < 80.89
90% CI is ( 79.11 to 80.89 )
orchestra answered 2 years agoRelated Solutions
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A simple random sample of 60 items resulted in a sample mean of
80. The population standard deviation is
σ = 5.
(a)
Compute the 95% confidence interval for the population mean.
(Round your answers to two decimal places.)
to
(b)
Assume that the same sample mean was obtained from a sample of
120 items. Provide a 95% confidence interval for the population
mean. (Round your answers to two decimal places.)
to
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