Answer:
The 98% confidence interval for the mean consumption of milk among people over age 32 is between 3.3 and 3.5 liters.
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 = 2.327.
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 3.4 - 0.1 = 3.3 liters
The upper end of the interval is the sample mean added to M. So it is 3.4 + 0.1 = 3.5 liters
The 98% confidence interval for the mean consumption of milk among people over age 32 is between 3.3 and 3.5 liters.