He should use a sample size of 655.
We can use the formula

We find the z-value by first subtracting the confidence level from 1:
1 - 0.8 = 0.2
Divide this by 2:
0.2/2 = 0.1
Subtract this from 1:
1 - 0.1 = 0.9
Using a z-table (http://www.z-table.com) we find the z-score associated with this is 1.28.
Now we plug our information into our formula:
C. F(x)=4x2-2x+16 .....:...
Answer:
$1.99 per pound
Step-by-step explanation:
5.97 / 3 = 1.99