Discrete vs Continuous variables: How to Tell the Difference

SOLVED:Decide whether a discrete or continuous random variable is the best model for each of the following variables: (a) The time until a projectile returns to earth. (b) The number of times a transistor in a computer memory changes state in one operation. (c) The volume of gasoline that is lost to evaporation during the filling of a gas tank. (d) The outside diameter of a machined shaft.

Continuous Probability Distribution