Confused About Estimating Probability

#1
In a study of 685 cars in a parking lot, there were only 3 different types: sedan, sports car and mini-van. 211 of the cars were mini-vans. Use this information to estimate the probability of choosing a car that is a sedan or sports car.

(I know that since 211 of the 685 cars are mini-vans that the other 474 cars are either sedans or sports cars but I'm a little confused about how to work the problem. Would I be dividing 211 into 685?)

Any help would be greatly appreciated!
 

Dragan

Super Moderator
#2
In a study of 685 cars in a parking lot, there were only 3 different types: sedan, sports car and mini-van. 211 of the cars were mini-vans. Use this information to estimate the probability of choosing a car that is a sedan or sports car.

(I know that since 211 of the 685 cars are mini-vans that the other 474 cars are either sedans or sports cars but I'm a little confused about how to work the problem. Would I be dividing 211 into 685?)

Any help would be greatly appreciated!
How's about estimating the probability as follows:


Pr{Sedan or Sports Car} = 1 - Pr{Mini-Van} = 1 - 211/685 = 0.69197...