Assume the speed of vehicles along a stretch of I-10 has an approximately normal distribution with a mean of 68 mph and a standard deviation of 6 mph.

a) The current speed limit is 65 mph. What percentage of vehicles less than or equal to the speed limit?

b) What proportion of the vehicles would be going less than 55 mph?

c) What is the percentage of vehicles going more than 95 mph?

d) A new speed limit will be initiated such that approximately 10% of vehicles will be over the speed limit. What is the new speed limit based on this criterion?