Question: (5 marks) It is known, as a result of testing over many years, that the mean functional lifespan of an established dental operating lamp under normal working condition is 365 hours. A new lamp has recently come to the market, costing about 5% more, and a dental practitioner has tested 10 of them. He finds that the mean functional lifespan of these ten lamps is 380 hours, with an estimated standard deviation of 30.3 hours. Is it worth his while investing in the new lamps or should he stick with the old?