A random sample of 49 lunch customers was taken at a restaurant

 

A random sample of 49 lunch customers was taken at a restaurant. The average amount of time the customers in the sample stayed in the restaurant was 45 minutes with a standard deviation of 14 minutes.

 

1-Compute the standard error of the mean.

 

 

2-With a .95 probability, what statement can be made about the size of the margin of error?

 

3-Construct a 95% confidence interval for the true average amount of time customers spent in the restaurant.

 

4-With a .95 probability, how large of a sample would have to be taken to provide a margin of error of 2.5 minutes or less?