goldant454

The queue manager at a bank believes that their clients spend, on average, less than 15 minutes in the queue. To test his belief the manager commissioned a study, which found out that, from a random sample of 80 customers, the average waiting time was 18 minutes. Assume a population standard deviation of 3 minutes and that the waiting time is approximately normally distributed.
(a) Formulate the null and the alternative hypothesis for this test situation. 
(b) Which test statistic (z or t) is appropriate for this test? Give a reason for your answer. 
(c) Conduct a hypothesis test for a single mean at 5% significance level. Interpret your results

A study has been performed on a client list of a local store to see if they would be interested in a new credit facility. The study has found the following: 383 out of 450 people would be interested in the credit facility.
Using this information, calculate a 99% confidence interval for the proportion of clients who will be interested in the new credit facility. Interpret your results.

The weights (in pounds) of three adult males are 160, 215, and 195. What is the standard error of the mean for these data?