Efer to the scheer industries example in section 8.2. use 6.85 days as a planning value for the population standard deviation. a. assuming 95% confidence, what sample size would be required to obtain a margin of error of 1 days (round up to the next whole number)? b. assuming 90% confidence, what sample size would be required to obtain a margin of error of 2.5 days (round up to the next whole number)?