If the average weight of a sample is 23 ounces, with a standard deviation of 0.4 ounces and a sample size of 16, what will be the control limits for the x-bar chart at +-3 sigma?
a. 22.90 to 23.10 ounces
b. 22.25 to 23.75 ounces
c. 21.8 to 24.2 ounces