Day Care Tuition A random sample of 50 four-year-olds attending day care centers provided a yearly tuition average of $3987 and the population standard deviation of $630. Find the 90% confidence interval of the true mean. If a day care center were starting up and wanted to keep tuition low, what would be a reasonable amount to charge

We have to find the 90% confidence interval for the mean

                 Given sample size  

                        Sample mean  

Population standard deviation  

Here the confidence level is 90% then  

                                                  And  

The 90% confidence interval is  

Here  is the critical value at 0.05

From the tables  

Now the 90% confidence interval is =

                                                                                     =

                                                                                     =(3840.44, 4133.56)

Hence the 90% confidence interval for the mean is (3840.44, 4133.56)

one that is bigger than 3 1/2

if i put something wrong your not gonna like it so rather not say nothing.