Please help on 7 and 8

I ll-le then randomly selects records on 47 laptops sold in the past and finds that the mean replacement time . ' I Question 7 7. 8011p: '53 1'0 899' Gut-ta The manager of a computer retail store is concerned that his suppliers have been giving him laptOp ' .Lyycomputers with lower than average quality. His research shows that replacement times for the model _;"lapt0p of concern are normally distributed with a mean of 3.2 years and a standard deviation of 0.5 years. Assuming that the laptop replacment times have a mean of 3. 2 years and a standard deviation of 0 5 years, find the probability that 47 randomly selected laptops will have a mean replacment time of 3 years or less. P(:_