Milky Way Galaxy right now.? Part A: On average, how many stars would we have to search before we would expect to hear a signal? Assume there are 500 billion stars in the galaxy. Express your answer using two significant figures.

Part B: How does your answer change if there are only 120 civilizations instead of 1.1×10^4? Express your answer using two significant figures.
There's another question on here that is labeled correct but I've entered those answers and they were in fact wrong. I have on more attempt remaining for each part. Please help, anything would be appreciated.