The average selling price of a smartphone purchased by a random sample of 31 customers was $299.Assume the population standard deviation was $32 a.Construct a 95% confidence interval to estimate the average selling 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 sand an upper limit of s (Round to the nearest cent as needed.) b.The margin of error is $(Round to the nearest cent as needed.