Probability Simulation

How do I go about simulating profits for an event that the spectators are based on weather.

Weather Probability
Clear .5
Cloudy .3
Rain .2
 If weather is clear, the number of spectator would be 1,500.
 If weather is cloudy, the number of spectator would be 1,000.
 If weather is rain, the number of spectator would be 300.

I know you're supposed to use Random numbers but I have no clue otherwise. If I find out the spectators through probability, I can calculate profit by myself.

How do I Set this up?