A soft-drink machine is being regulated so that the amount of drink dispensed averages 240 milliliters with a standard deviation of 15 milliliters. Periodically, the machine is checked by taking a sample of 40 drinks and computing the average content. If the mean of the 40 drinks is a value within the interval px ± 2a x , the machine is thought to be operating satisfactorily; otherwise, adjustments are made. In Section 8.4, the company official found the mean of 40 drinks to be x = 236 milliliters and concluded that the machine needed no adjustment. Was this a reasonable decision?