In Problem 21 from Section 10.3, we considered the mean waiting time at the drive-through of a

Question:

In Problem 21 from Section 10.3, we considered the mean waiting time at the drive-through of a fast-food restaurant. The manager is also worried about the variability in wait times. Prior to the new drive-through system, the standard deviation of wait time was 18.0 seconds. Use the data in the following table to decide whether the evidence suggests the standard deviation of wait time is less than 18.0 seconds. In Problem 21 from Section 10.3, we verified the data could come from a population that is normally distributed. Use the a = 0.05 level of significance.