Final answer:
The probability that two people have a birthday on the 9th of any month is approximately 0.1081%, which is calculated by multiplying (12/365) for the first person by (12/365) for the second person.
Step-by-step explanation:
The probability that two people have a birthday on the 9th of any month can be calculated by considering that there are 12 possible days in a year that fall on the 9th of a month. The probability that one person has a birthday on a specific date, like the 9th, is 1/365, since there are 365 days in a non-leap year.
However, since we are only considering the 9th of any month, this increases the chances to 12/365 for one person. To find the probability for two people, we multiply their individual probabilities together. Therefore, the probability that both people selected have a birthday on the 9th of any month is (12/365) * (12/365), which simplifies to (144/133,225) or approximately 0.001081, which is a little more than 0.1%