Coffee: A popular chain of cafes has been receiving online

Last updated: 7/8/2022

Coffee: A popular chain of cafes has been receiving online complaints about one store location. Regular customers complained that the staff at this location consistently underfill their cups of coffee. The owner of the chain will personally visit the location to meet with the staff to determine if more than 10% of the 16 ounce cups are underfilled by 1 fluid ounce. She arranges to have "mystery shoppers" visit the store. Mystery shoppers are people who are paid to pose as a regular customer and provide feedback to the owner about customer service. After 100 mystery shop visits, she finds that 18 of the 16 ounce cups of coffee were underfilled. She plans to test the hypotheses Ho: p = 0.10 versus Ha: p > 0.10. What is the test statistic? A. z = -2.08 B. z = -2.67 C. z = 2.08 D. z = 2.67