An Answer Page for Exercise 11

Exercise 11

Show that about 45% of the winning pass line bets are made on the come out roll.
Hint:   P( natural | win ) = ?



Let p   =   P( win )   =   244 / 495

Let natural   =   The event of rolling 7 or 11

The only way you can win on the come out is to roll a natural.

So,   P( win on come out | win )   =   P( natural | win )

  P( natural | win ) = P( natural and win ) / P( win )
  = P( natural ) / P( win )
  = ( 8 / 36 ) / ( 244 / 495 )
  = ( 2 / 9 ) * ( 495 / 244 )
  = 55 / 122     45.1%

So,   given that you won,   the probability that you won on the come out is about 45%.