Probability (general terms)
The odds are an indication of what the odds layer thinks is
the probability of a participant winning an event. If you were
to add up the probabilities of each participant they have to
total exactly 100% (one participant - but only one - must win).
You can calculate the probabilities from the odds (there’s
an example table below). To calculate the percentage, divide
100 by the sum of the two parts of the ratio and then multiply
the result by the second part of the ratio. For 11-4 this works
out as 100 divided by 15 (11 plus 4) equals 6.666. This multiplied
by 4 gives 26.67 Converting the odds to percentages is particularly
useful for calculating the overround.