probability

Owen's tosses could be:

WWW     *

WWL      *

WLW      *

WLL       *

LWW      *

LWL       *

LLW       *

LLL

 

Of the 8 possibilities, 7 have at least one winner.

We need to consider only these 7 possibilities.

One of these seven has all three winners     --->     Probability  =  1/7