Answer:
The probability of getting the toy you want in any given cereal box is p=0.056.
Step-by-step explanation:
On average, you get the toy you want in every 18th cereal box.
This value corresponds to the mean of a geometric distribution, where it is expected that you get 17 "failures" before the first "success".
The mean of the geometic distribution, whose value is 18, can be written as:
where p is the probability of "success": getting the collector's toy you want.
Then, p has a value of 1/18≈0.056.