A soft drink company has recently received customer complaints about its one-liter-sized soft drink products. Customers have been claiming that the one-liter-sized products contain less than one liter of soft drink. The company has decided to investigate the problem. According to the company records, when there is no malfunctioning in the beverage dispensing unit, the bottles contain liters of beverage on average, with a standard deviation of liters. A sample of bottles has been taken to be measured from the beverage dispensing lot. The mean amount of beverage in these bottles was liters. Find the probability of observing a sample mean of liters or less in a sample of bottles, if the beverage dispensing unit functions properly.