Question: The police was trying to catch drivers who pass the speed limit on a highway. The device they’ve been using records the speed. And we know it’s normally distributed with a mean of 85 and standard deviation of 12.

A. On this highway, a driver who drives under 70 km/h disrupts the traffic. What’s the % of drivers who do NOT disrupt the traffic?

B. What’s the third centile of the drivers’ driving speed on this highway?

C. What’s the symmetrical boundaries around the mean that include 50% of the drivers on this highway?