A toy manufacturer wants to see how long, on average, a new toy captures children's attention. He tests 17 children selected at random and finds that their mean attention span is 19 minutes with a standard deviation of 4 minutes. If we assume that attention spans are normally distributed, find a 90% confidence interval for the mean attention span of children playing with this new toy. Give the lower limit and upper limit of the 90% confidence interval. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.) Lower limit: ! X Upper Limit