Answer:
The percentage of fat in the mixture is 8%
Step-by-step explanation:
Let
x -----> the percentage of fat in the mixture
we know that
The volume of milk multiplied by its percentage of fat plus the volume of cream multiplied by its percentage of fat must be equal to the total volume of he mixture multiplied by the percentage of fat in the mixture
Remember that
15%=15/100=0.15
3%=3/100=0.03
so
Solve for x
Convert to percentage
Answer:
We need a sample size of at least 425.
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 manager would like to be 99% confident that their estimate of the mean is within 0.05 ounces of the true mean, how large of a sample is needed?
We need a sample size of at least n.
n is found when . So
Rounding up
We need a sample size of at least 425.