Poker: Am I making profit or just getting lucky?

Hi,

Using normal distribution and/or bayes' theorem I'm trying to work out the probability that I'm making a profit and not just having good luck.

I'm interested in the maths so that I can calculate this for future scenarios.

The example scenario:

The game: SNG. 10 Players, $1 entry. Payout: 1st: $5. 2nd: $3. 3rd: $2.

The sample: 5 games played, net profit: $10. ($5 spent, $15 won)

What is the probability that the 5-game sample above represents an underlying population of games where I'm on average breaking even or better?

From what I've deduced, there are at least two ways of calculating this, each with different answers?? The book I'm reading, "The mathematics of poker" (I think!!) says that one way would use bayes' theorem and one wouldn't?

Help appreciated!