1.The sample mean is 12; the sample standard deviation is 5; and the sample size
ID: 3074760 • Letter: 1
Question
1.The sample mean is 12; the sample standard deviation is 5; and the sample size in a research study is 25. Calculate the 95% confidence interval for the population mean
[2.064; 14.064]
[9.936; 14.064]
[2.064; 9.936]
None of the above
2.
When is the t distribution the correct distribution for calculating confidence intervals for the population mean?
When the population standard deviation is unknown and population is non-normal
For small samples.
For small samples only when population standard deviation is known
When the population standard deviation is unknown and the population is distributed normal.
For finite populations with large samples.
None of the above is true
[2.064; 14.064]
[9.936; 14.064]
[2.064; 9.936]
None of the above
Explanation / Answer
x= 12
n= 25
Df= 24
s= 5
alpha=0.05 then T(alpha/2)=2.06389
Margin of error E=T(alpha/2)*s/sqrt(n)
=2.06389*5/sqrt(25)
=2.06389
95% Confindence interval for population mean =(x-E,x+E)
rounded upper bound= 14.064
rounded lower bound= 9.936
correct option is B
....................
When the population standard deviation is unknown and the population is distributed normal.
...............
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