4. (8 points) According to some studies, a vacuum cleaner uses an average of 46 kilowatt hours per year. If a sample of 12 homes shows that vacuum cleaners use an average of 42 kilowatt hours per year with a standard deviation of 11.9 kilowatt hours, does this suggest at the 0.05 level of significance that vacuum cleaners use, on average, less than 46 kilowatt hours annually? Conduct an appropriate test to answer this. Assume the population of kilowatt hours to be normal