The owner of company that operates fixed green minibus route wishes to study the daily mileage of the company 's 42 minibuses . Form past experience , the
distribution of the daily mileage is normally distributed with a mean of 168 KM
and a standard deviation of 86 km .on a particular day, a sample of six minibuses is chosen randomly and the corresponding mileage is recorded .
1.what is the mean and standard deviation of the sample mean??
thx..
更新1:
company 's = company ' s