In Keno, which selection numbers is less -EV for the bettor?

[kinghippo423]

Hello,

I had an argue with a friend in the last week-end when we walked in the Keno Room. We had a positive night on the tables so we when relaxing in the Keno Room (weird but true). We tried to figured out how many numbers the bettor should take to have the best expected value on his money. We tried our theory by putting our answer to the test. I took 20 numbers and he took 7.

Of course we lost our $2 bucks with a smile but we were angry because we couldn't find the right answer rationaly and not by feelings so I thought someone here on this forum knows the answer and is willing to tell me why.

So my question is which selection numbers (between 1 - 20)is less -EV for the bettor?

Thanks in advance