Hammon Case Problem - Hypothesis Testing
THE PROBLEM:
Your friend Elizabeth is the owner of a trendy delicatessen in downtown Seattle, Washington called Zeli's Deli, which is actually stationed on a food truck. It is known for its delectable sandwiches. One of the most popular is The Zelda which is served with a mountain of home fries and special Zim sauce. The deli serves primarily professional clientele downtown such as accountants and attorneys who have demanding schedules and require prompt lunch service. Though the deli focuses on unique and high quality sandwiches, they also advertise fast service during the primary lunch hours of 11:00 - 1:00.
There is some question as to whether the population mean waiting time to place an order has changed in the past month from its previous population mean value of 4.5 minutes. Elizabeth wants to ensure Zeli's Deli is still meeting the ad's claim and satisfying her clientele with low wait times. She knows you are taking a business statistics class and are really good at it, and has asked you to help her find the answer.
Because you are good at stats you feel confident that you can help your friend. So the following Monday you go downtown to visit Zeli's Deli during the busy lunch time and randomly select a sample of 25 orders during a one-hour period. The sample mean is 5.1 minutes. Assume the population is normally distributed and has population standard deviation of 1.2 minutes. Complete the requirements section and be sure to address all questions listed below. (Hint this is a two-tailed test.)
You may use either the classical or p-value approach. There is no need to present both in your result. Either approach should yield the same result.
REQUIREMENTS:
Step 1: In your own words write a sentence describing the question/problem to test.
Step 2: State the null and alternative hypotheses.
Step 3: Use 0.05 for the alpha level of significance.
Step 4: Compute the Z statistic.
Step 5: Interpret your results using either the classical or p-value approach. What are your findings? How confident are you?
Step 6: Properly state your decision regarding the null and alternative hypotheses.
Step 7: Draw a curve showing your findings.