toss a dime, the chance of getting head up is 1/2. toss two dimes, the chance of getting two heads up is 1/2 (1/2) =1/4 , the 1/2 in the bracket is the chance of getting head up for the second dime, giving the first dime heads up. it's the same as the chance of getting head up without the first dime. This is called probalisticly independent.

the expert win = he beats all novices = all novices fail to win him = 1st novice fails, same time 2nd one fails, same time(1st and 2nd both fail) 3rd one fails ...

assume whether a novice beat the expert or fail is not influenced by other novice or novices at all. and the chance is p

1st 2nd 3rd 4th 5th 6th 7th 8th 9th novice

p p p p p p p p p =0.48 chance of everyone fails