Mr. Gomez wants to put a ceramic tile border along all four sides of his kitchen wall.Mr. Gomez has measured and knows he needs
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Answer:
The 95% confidence interval for the population mean is between 17.93 days and 24.07 days.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
So it is z with a pvalue of , so
Now, find M as such
In which is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 21 - 3.07 = 17.93 days
The upper end of the interval is the sample mean added to M. So it is 21 + 3.07 = 24.07 days
The 95% confidence interval for the population mean is between 17.93 days and 24.07 days.