Using the probability and odds concepts, it is found that the odds against it containing a number greater than or equal to 7 is .
A probability is the <u>number of desired outcomes divided by the number of total outcomes</u>.
An odd is the <u>number of desired outcomes divided by the number of non-desired outcomes</u>.
In the rack, there are 15 balls, numbered from 1 to 15. Of those, <u>6 are less than 7</u>(against it containing a number greater than or equal to 7 is equivalent to it containing a number less than 7), thus:
There are 6 desired outcomes.
There are 9 non-desired outcomes.
The odd is:
The odds against it containing a number greater than or equal to 7 is .