The owners of an eyeglass store claim that they fill customers' orders, on average, in 60 minutes with a standard deviation of 15.9 minutes. based on a random sample of 40 orders, a reporter determines a mean order time of 63 minutes. let µ represent the average number of minutes to fill an order. z = startfraction x overbar minus mu over (startfraction sigma over startroot n endroot endfraction) endfraction to the nearest hundredth, the z-statistic is:____.
