Confidence Intervals for Population Mean: Videos & Practice Problems

A beverage company uses a machine to fill bottles with juice. The company wants to estimate the average volume of juice dispensed by the machine to be within $0.5$ fluid ounce of the true mean. Assume the population of volumes is normally distributed with a known standard deviation of $0.75$ fluid ounce. What is the minimum sample size needed to construct a $90\%$ confidence interval for the population mean?