Answer:
The 95 percent confidence interval for the population mean is between 14.736 tons and 16.864 tons.
Step-by-step explanation:
We have the population's standard deviation, so we can find the normal confidence interval.
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.
The lower end of the interval is the sample mean subtracted by M. So it is 15.8 - 1.064 = 14.736 tons
The upper end of the interval is the sample mean added to M. So it is 15.8 + 1.064 = 16.864 tons
The 95 percent confidence interval for the population mean is between 14.736 tons and 16.864 tons.