A manager of a supermarket believes that self-check out lanes lead to higher customer satisfaction. To test this, satisfaction ratings were collected from a group of customers prior to the introduction of the lanes, and from an independent group of customers after the lanes were introduced. Let u be the increase in satisfaction rating. What would be an appropriate test to verify the manager's claim? (i.e. write down the null and alternative hypotheses) (you may use the Math editor ("fx") OR you may use these symbols: mu for population mean, >= for greater than or equal to, <= for less than or equal to, != for not equal to)