a. Assuming that the cleaning and preparation times are approximately normally distributed, calculate a range of values that contains almost all (approximately 99.73 percent) of the individual cleaning and preparation times.
b. Find reasonable estimates of the maximum and minimum times needed to clean and prepare an individual room.
c. Suppose the resort hotel wishes to specify that every individual room should be cleaned and prepared in 20 minutes or less. Is this upper specification being met? Explain. Note here that there is no lower specification, since we would like cleaning times to be as short as possible (as long as the job is done properly).
d. If the upper specification for room cleaning and preparation times is 20 minutes, find the sigma level capability of the process. If the upper specification is 30 minutes, find the sigma level capability.