This problem is about the difference between distance and displacement. The distance is how many kilometers has the car covered, the displacement is how far from the original point is the car now, and does not depend on the path followed, but it is the shortest path that connects two points.
a) In this part, they ask you for the distance. From the southernmost to the northernmost point of the circumference, the car has traveled half of the circumference, therefore: distance = circumference ÷ 2 = 2.7km ÷ 2 = 1.35km
b) In this part, you are asked for the displacement, which in this case is the diameter of the circumference: displacement = diameter = circumference ÷ π = 2.7km ÷ 3.14 = 0.86km = 860m
The probability that a random variable is greater than or equal to z standard deviations from the mean in a standard normal distribution he P(z≤a)+P(z>a)=1, so P(z>a)=1-P(z≤a)=1-.7116=.2884
