Answer:
The minimum sample size needed to be 95% confident that the sample mean is within 4 dollars of the true population mean is 47.
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 the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
If the population standard deviation is 14 dollars, what minimum sample size is needed to be 95% confident that the sample mean is within 4 dollars of the true population mean
This is n when . So
The minimum sample size needed to be 95% confident that the sample mean is within 4 dollars of the true population mean is 47.