It is not possible for the X-bar chart to be out-of- control when the R chart is in control. O True O FalseCommon causes of variation represent variation due to the inherent variability in the system. True O FalseAn appliance manufacturer claims to have developed a compact microwave oven that consumes an average of no more than 250 W. From previous studies, it was determined that power consumption for microwave ovens is normally distributed with a standard deviation of 15 W. A consumer group is suspicious of the claim and believes it is false. They take a sample of 20 microwave ovens and find that they consume an average of 257.3 W. Referring to the problem statement, for this test to be valid, it is necessary that the power consumption for microwave ovens has a normal distribution