Question

A toy manufacturer wants to see how long, on average, a new toy captures children's attention. he tests children selected at random and finds that their mean attention span is minutes with a standard deviation of minutes. if we assume that attention spans are normally distributed, find a confidence interval for the mean attention span of children playing with this new toy. then find the lower limit and upper limit of the 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:

upper limit:

Answer 1

Answer: Lower CI=21-t(0.025, 16)*7/sqrt(17)=21-2.12*7/sqrt(17)=17.4

upper CI=21+t(0.025, 16)*7/sqrt(17)=21+2.12*7/sqrt(17)=24.6

Explanation: Because there both close and equal