Question

The marketing director of a large department store wants to estimate the average number of customers who enter the store every five minutes. She randomly selects five-minute intervals and counts the number of arrivals at the store. She obtains the figures 51, 32, 41, 47, 56, 80, 49, 29, 32, and 80. The analyst assumes the number of arrivals is normally distributed. Using these data, the analyst computes a 95% confidence interval to estimate the mean value for all five-minute intervals. What interval values does she get?

Appendix A Statistical Tables

(Round the intermediate values to 2 decimal places. Round your answers to 2 decimal places.)

Answer 1

sample mean         x=	49.700
sample size             n=	10.000
sample std deviation s=	18.306
std error sx=s/√n=	5.7890

for 95% CI; and 9 df, critical t=		2.2620
margin of error E=t*std error                            =		13.095
lower bound=sample mean-E =		36.61
Upper bound=sample mean+E=		62.79

from above 95% confidence interval for population mean =(36.61,62.79)

(please try 36.60 , 62.80 ) if this comes wrong)