Answer:
The UCL of the 95% confidence interval for population mean is 10.16 minutes
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 .
That is z with a pvalue of , so Z = 1.96.
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.
The upper end of the interval is the sample mean added to M. So it is 9.3 + 0.86 = 10.16 minutes.
The UCL of the 95% confidence interval for population mean is 10.16 minutes