Finding outliers on simple dataset?

#1
Hello everyone! I have not worked with statistics since high school, but unfortunately am facing answering this simple question which has been overwhelming me! I've been googling information on calculating outliers in excel, but explanations I have found have not accounted for cases where the sample size is very small, which I have many of.

I am given the following data on 1,000 hypothetical slot machines:

Attempts made, wins, payout, payout per attempt (win rate * payout)

Some slot machines have over 15,000 attempts, while others have as few as 50. Here is what I'm wondering:

What is the best way assess which machines have payout per attempt values that can be classified as outliers? Seeing as some machines have so few attempts.

How can I determine the statistical significance of a given payout per attempt value when comparing it to a specific number? For example if as a gambler I want to target machines with higher than X payout per attempts?

Thank you so much!