Intravenous fluid bags are filled by an automated filling machine

Intravenous fluid bags are filled by an automated filling machine. Assume that the fill volumes of the bags are independent, normal random variables with a standard deviation of 0.08 fluid ounce.

(a) What is the standard deviation of the average fill volume of 20 bags?

(b) If the mean fill volume of the machine is 6.16 ounces, what is the probability that the average fill volume of 20 bags is below 5.95 ounces?

(c) What should the mean fill volume equal in order that the probability that the average of 20 bags is below 6 ounces is 0.001?