The average selling price of a smartphone purchased by a random sample of 41 customers was $306. Assume the population standard deviation was $34 a. Construct a 95% confidence interval to estimate the average soiling price in the population with this sample b. What is the margin of error for this interval? a. The 95% confidence interval has a lower limit of and an upper limit of (Round to the nearest cent as needed) b. The margin of erroris $(Round to the nearest cont as needed.)