If we have a 10 runner horse race and we perceive the probabilities of winning the as follows...

Horse 1 35%

Horse 2 15%

Horse 3 10%

Horse 4 10%

Horse 5 10%

Horse 6 5%

Horse 7 5%

Horse 8 4%

Horse 9 3%

Horse 10 3%

how would formulate the chance of a single horse finishing either first, second or third? Or would the probabilities of winning the race not be enough?

p.s. I'm no maths expert so a dumbed down version would do if possible.

Thanks,

Adam.