Chapter 4: Rational Numbers: Positive and Negative Fractions Numbers in the Real World

Oddly Enough

You have probably heard of  "2 to 1" odds or "20 to 1 longshot."  If someone bets on a horse with 20 to 1 odds, then he or she is betting $1 for that horse to win against someone betting $20 for that horse to lose.  The reason that a horse would have 20 to 1 odds is that the horse would only be expected to win 1 time and lose 20 other times.  In other words, the horse would win 1 in 21 races, or a probability of 1/21.

In other words, convert odds  a to b  to probability ^b/_a+b.

There are a number of Internet sites that list the odds for upcoming horse races.  Search for one of those sites, and compute the probability that different horses would win the race.

On the other hand, what if you knew the probability of the horse winning was ¹/₄₅?  The odds would be 44 to 1.

Look at the back of a lottery ticket.  The chances of winning are 1 out of some huge number.  Convert that probability into the odds of winning.