Probability and the Birthday Paradox
Ever wondered why it's more likely than you think to share a birthday with someone in a room of just 23 people? Welcome to the intriguing world of the Birthday Paradox, a fascinating example of how probability can defy our intuition.
The Birthday Paradox
The birthday paradox, also known as the birthday problem, states that in a random group of 23 people, there is about a 50 percent chance that two people have the same birthday.
- When all 23 birthdays are compared against each other, it makes for much more than 22 comparisons, so 253 combinations.
Extra: roll dice 100 times and record the results
Calculate the mathematical probability of getting a sum higher than 18 for each combination of dice when rolling them 100 times
- Which combination has a higher mathematical probability, and was this true when you rolled them?
- Probability Central from Oracle ThinkQuest
Observations and results
Did about 50 percent of the groups of 23 or more include at least two people with the same birthdays?
- When comparing probabilities with birthdays, it can be easier to look at the probability that people do not share a birthday.
- A person’s birthday is one out of 365 possibilities (excluding February 29 birthdays).
- The probability that a person does not have the same birthday as another person is 364 divided by 365 because there are 364 days that are not a person’s birthday.
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