A school zone on posted a speed of 50km/hr.The speed of vehicles passing through the school zone are normally distributed with the mean of 56km/hr and a standard deviation of 4km/hr.Find the percentage of vehicle passing through the school zone that are:

a.) Exceeding the posted speed limit
b.) Travelling at speeds between 60km/hr

You can play around with Z table stuff at

davidmlane.com/hyperstat/z_table.html