Bachelor Party - How bad are these odds??

[scatthecat]

At my cousin's bachelor party this past weekend, there was a dice game set up in which 3 normal 6 - sided dice were rolled in a cage, and their total was counted to get a number between 3 and 18.

You could put down your cash on any of the 16 numbers, and each one paid out 10 to 1 if the number was rolled.

Obviously, I thought. . . you'd have to be a dimwit to put your green down on any number even close to 3 or 18.

But after 10 came up three times in a row, the gent next to me exclaimed 'Whoa!! That number's done, I'm not putting anything down on 10 for another hour!' and shifted his ones down to the four and the five ('cause triple snake eyes is pretty unlikely').

Just for fun, assuming that you kept your money solely on 10 and 11, what would the 'house edge' in this game be? How bad is it on 3 or 18??

I think I figured it out but just wanted some confirmation, if anyone's interested in it!

Later guys,

-scat