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(6 marks) Tenaga Nasional Berhad (TNB) has listed a variety of home appliances each with annual total electricity consumption in kilowatt-hours. For a medium sized refrigerator, the annual electricity consumption is on average of 46 kilowatt-hours. A random sample of 12 homes included in the study showed that medium sized refrigerators consume the electricity at an average of 42 kilowatt-hours per year with a standard deviation of 11.9 kilowatt-hours. At a significance level of 0.05 and assuming that, the population is normal, does this sample show that medium sized refrigerators consume, on the average, less than 46 kilowatt-hours per year