The yield of a chemical process is being studied. From previous
experience, yield is known to be normally distributed
and σ=3. The past five days of plant operation have
resulted in the following yields 91.6, 88.75, 90.8, 89.60, and
91.6. Find a 95% two-sided confidence interval on the true mean
yield.
(a) Calculate the sample mean. Round your answer to 2 decimal
places.
(b) Calculate the 95% two-sided confidence interval on the true
mean yield. Round your answers to 1 decimal place.