i believe your answer will be 0.04 or 4/100
OR if you need an equivalent expression, that would be 81/2187
Answer:
The sample must be of at least 48 pizzas.
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.
How large a sample must she take if she wants the margin of error to be under 0.5 inch?
She needs a sample of at least n, in which is found when 






Rounding up
The sample must be of at least 48 pizzas.