A supermarket has just added a new cash register to reduce the waiting times of the customers during weekends. Since a new cash register is added, the customers expect that their waiting time will be less than the waiting time before the cash register was added. Suppose the sample variance of the waiting times for 25 customers before adding the new cash register is sĩ = 4.8 minutes, while the sample variance of the waiting times for 25 customers after adding the cash register is sź = 2.2 minutes. The manager of the supermarket believes that the waiting times are normally distributed and that the two samples are drawn independently. What is the conclusion? Given that all other criteria are satisfied, should the supermarket continue with the new cash register?
A supermarket has just added a new cash register to reduce the waiting times of the customers during weekends. Since a new cash register is added, the customers expect that their waiting time will be less than the waiting time before the cash register was added. Suppose the sample variance of the waiting times for 25 customers before adding the new cash register is sĩ = 4.8 minutes, while the sample variance of the waiting times for 25 customers after adding the cash register is sź = 2.2 minutes. The manager of the supermarket believes that the waiting times are
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