Normal distribution a,b,c

6. A construction zone on a highway has a posted speed limit of 40 miles per hour. The speeds of vehicles passing through this construction zone are normally distributed with a mean of 46 miles per hour and a standard deviation of 4 miles per hour. a) Find the percentage of vehicles passing through this construction zone that are exceeding the posted speed limit. b) What proportion of vehicles passing through this construction zone are going between 39 and 48 miles per hour? c) The fastest 10% of the vehicles passing through this construction zone are going at what speed