1.For certain types of laptops, the length of time between charges of the battery is normally distributed with a mean of 8 hours and a standard deviation of 1.75 hours when in full use. A store owner randomly chose a sample of 32 laptops from his stock.

a)What is the sampling distribution of the mean length of time of these 32 laptops?Give the distribution, the mean and the standard deviation.

b)What is the probability that the mean length of time is less than 8.5 hours?