The manager of a Steelton based store is concerned about a possible slowdown in payments from her customers. She measurers the rate of payments in term of the average number of days receivables are outstanding. Generally, the store has maintained an average of $50$ days. A random sample of $25$ accounts gives an average of $54$ days outstanding with a standard deviation of $8$ days. Perform a hypothesis test for the average number of days receivables outstanding.