What is the sample space for this situation?

Question

A telephone sales representative makes successive calls to potential customers, and the result of each call is recorded as a sale (S) or a no sale (N). Calls are continued until either two successive sales are made, two calls result in no sale (these calls need not be consecutive), or a total of 4 calls is made. What is the sample space for this situation.

Answer 1

We must have at least 2 calls to meet the stopping condition. But once 4 calls are made, the stopping condition is automatically met. Therefore, the sample space is {2,3,4}.