Police use a radar unit is used to measure speeds of cars on a freeway. The speeds are normally distributed with a mean of 90 km/hr and a standard deviation of 10 km/hr.
(a) What is the probability that a car picked at random is traveling at more than 100 km/hr?
(b) Since normal distributions technically have a domain of (-00,00), this distribution allows the speed of a car to be negative. But does it really!? Determine (or try to) the probability that the speed of a car is negative and decide for yourself if this is at all possible.
Note: As always when you answer a question with a normal distribution, you must show a shaded PDF indicating the region you are trying to calculate.