Hypothesis testing for single mean.
The MacBurger restaurant chain claims that the waiting time of customers for service is normally distributed, with a mean of 3 minutes and the standard deviation of 1 minute. The quality-assurance department found in a sample of 50 customers at Warren Road MacBurger that the mean waiting time was 2.75 minutes. At .05 significance level, can we end that the mean waiting time is less than 3 minutes?