A researcher would like to determine whether a new tax on on cigarettes has had any effect on people's behavior. During the year before the tax was imposed, stores located in rest areas on the state freeway reported selling an average of mew = 629 packs per day with sigma = 73. The distribution of daily sales was approximately normal. For a sample of n=14 days following the new tax, the researcher found an average of 431 packs per day for the same stores. Find and report the value of the appropriate test statistic to two decimal places.