The manager of a computer retails store is concerned that hissuppliers have been giving him laptop computers with lower thanaverage quality. His research shows that replacement times for themodel laptop of concern are normally distributed with a mean of 3.7years and a standard deviation of 0.5 years. He then randomlyselects records on 37 laptops sold in the past. Round the answersof following questions to 4 decimal places. What is thedistribution of X ? X ~ N( , ) What is the distribution of ¯ x ? ¯x ~ N( , ) What is the probability that one randomly selectedlaptop is replaced less than 3.6 years? For 37 laptops, find theprobability that the average replacement time is less than 3.6year. For part d), is the assumption of normal necessary? YesNo
