posted by lerato on .
a countrywide estate agency specializes i selling commercial ventures. their records show that the mean selling time is less than 90 days. because of recent economic conditions, they believe that the mean selling time is now greater than 90 days. a countrywide survey of 100 businesses sold recently revealed that the mean selling time was 94 days, with a standard deviation of 22 days. at the 0.10 level of significance, has there been an increase in selling time?