A paint manufacturer uses a machine to fill gallon cans with paint (1 gal = 128 ounces). The manufacturer wants to estimate the mean volume of paint the machine is putting in the cans within 0.6...

i only get half of it right, having trouble on this one

Extracted text: A paint manufacturer uses a machine to fill gallon cans with paint (1 gal = 128 ounces). The manufacturer wants to estimate the mean volume of paint the machine is putting in the cans within 0.6 ounce. Assume the population of volumes is normally distributed. (a) Determine the minimum sample size required to construct a 90% confidence interval for the population mean. Assume the population standard deviation is 0.70 ounce. (b) The sample mean is 126.75 ounces. With a sample size of 5, a 90% level of confidence, and a population standard deviation of 0.70 ounce, does it seem possible that the population mean could be exactly 128 ounces? Explain. Click here to view page 1 of the Standard Normal Table. Click here to view page 2 of the Standard Normal Table. (a) The minimum sample size required to construct a 90% confidence interval is (Round up to the nearest whole number.) cans.