Fowle Marketing Research, Inc., bases charges to a client on the assumption that telephone surveys can be completed in a mean time of 15 minutes or less. If a longer mean survey time is necessary, a premium rate is charged. A sample of 35 surveys provided the survey times shown in the WEBfile named Fowle. Based upon past studies, the population standard deviation is assumed known with = 4 minutes. Is the premium rate justified? Click on the webfile logo to reference the data.