IF, AND, OR conditions in the same formula

[FM1]

Column A = "Status". Values: Unassigned, In Progress, Rejected, Not Proceeding and Complete
Column B = "Date Closed". Values: Date

I need a statement where I get a 1 value when all the following conditions are met:

1. Date Closed is not blank
AND
2. Status = "In Progress" OR "Unassigned"

 

[mikerickson]

One can set Validation to Warning or Information. The user is then warned, but not absolutely forbidden to enter an invalid entry.