Totalizators or flexible-rate bets. These totalizators are risk-free for the bookmaker. In these flexible-rate bet games the odds are influenced by the share of exchange each of the results have received taking in to account the return rate of bookmaker offering the game. If the returned percentage is let’s say 80%, this means that of the amount placed on the bet, 80% will be given back to bettors as winnings.

Naturally the more money bet on the option, the smaller the coefficient.

Example of a totalizator:

Football game Liverpool-ManU, the target of the bet is the outcome with the number of goals scored. This target is played with a total of 100 000 euros, so as winnings 80 000 will be dealt. The final score is 1-1, which has been bet with a total of 10 000 euros. This 1-1 scores represents 10% of all the bets made. Taking into account the return percentage of 80%, the 1-1 score would have the coefficient of 8.

This comes by counting the 10 000 share of the 100 000 euros, which is 10%, the reciprocal will make a coefficient of 10, which still need to be divided by 0,8 (the return percentage). This is how every other final score could be counted, depending on the amounts of bets made on them.

sources: #1