What's the chance that two people share the same birthday? The first person can be born on any day of the year, this means that the probability is 365/365 = 1. The second person has to be born on the same day as the first and there is a 1/365 chance of that happening.
Due to probability, sometimes an event is more likely to occur than we believe it to. In this case, if you survey a random group of just 23 people there is actually about a 50–50 chance that two of them will have the same birthday. This is known as the birthday paradox.
The probability of sharing a birthday = 1 − 0.294... = 0.706... Or a 70.6% chance, which is likely! So the probability for 30 people is about 70%.
In probability theory, the birthday problem asks for the probability that, in a set of n randomly chosen people, at least two will share a birthday. The birthday paradox refers to the counterintuitive fact that only 23 people are needed for that probability to exceed 50%.
Why the Odds are Actually Much Higher! One person has a 1/365 chance of meeting someone with the same birthday. Two people have a 1/183 chance of meeting someone with the same birthday.
The most common birthday is Sept. 9. In second and third place are Sept. 19 and 12. In fact, the entire top 10 list is made of September birthdays between Sept. 9 and 20. Count backward and you're just in time for the holidays, since pregnancy is an average of 40 weeks from last menstruation.
Because we all know that we only have control over one of those things. So, although the 9th of September is the most common birthday in the world, it's time to look at what may influence more people to conceive nine months before that – that is, mid-December, or the 9th if you'd like to be precise.
What's the chance that two people share the same birthday? The first person can be born on any day of the year, this means that the probability is 365/365 = 1. The second person has to be born on the same day as the first and there is a 1/365 chance of that happening.
December 25 (Christmas Day) is the least common birthday, while January 1 (New Year's Day) is the second least common. December 24 (Christmas Eve) also makes the list as the 3rd least common birthday while July 4 (Independence Day) is the 4th least common birthday.
The birthday paradox - also known as the birthday problem - states that in a random group of 23 people, there is about a 50% chance that two people have the same birthday. In a room of 75 there's even a 99.9% chance of two people matching. The birthday paradox is strange, counter-intuitive, and completely true.
There are so many special things about your May baby… including the day they were born. Only one May birthdate cracks the top 100 popular birthdays (May 23rd lands in 89th place).
Conversation. I am both does that count? 8 billion people have a birthday, but as it goes, 365 birthdays are spread throughout the year celebrated by many people (leap years include 366).
Your April baby's birthday is pretty rare.
Your little one is unlikely to need to share the limelight on their birthday because April birthdays are not super common. Only two April birthdates made their way into the top 200 most popular birthdays (April 4th at 144th and April 11th at 189th), while 11 landed below 300.
The birthday paradox is strange, counter-intuitive, and completely true. It's only a “paradox” because our brains can't handle the compounding power of exponents. We expect probabilities to be linear and only consider the scenarios we're involved in (both faulty assumptions, by the way).
Think of it this way: if you were born in 1960, your Beddian year is 2020, the year you turn 60. 1960 + 60 = 2020.
Your golden birthday is when you reach the age that corresponds to the day you were born on. If you're born on the 10th, then your golden birthday is when you turn ten years old. 2.
February 3rd is the only day where no one in history has ever been born. Despite much scientific study, there is no explanation for this phenomena. Historically it has been referred to as “the empty day” or “nobody's birthday”.
Apparently astrologers have a term for this, 'date-twins'. If the details are precisely the same then they call them astro-twins.
In their early years, preemies are sometimes thought to have two days that represent a birthday. The first is the actual day that the baby was born, and the second is the day the baby was originally due.
Since the world population is estimated at over seven and a half billion,1 you should, in theory, share your birthday with over 20 million people (~20,438,356).
Did you see the most and least common dates? If not here they are: The most common birthday in Australia is September 17th! The least common birthday (you may have guessed it is) is Christmas Day, the 25th of December.
What are the rarest birthdays? Surprisingly, none is in February. They cluster around holidays. December 25, January 1, December 24, July 4, January 2, December 26, November 27, November 23, November 25 and October 31st.
What is a Golden Birthday? Your golden birthday is when the date of your birth coincides with your age. For example, if you were born on October 8, your golden birthday took place when you turned 8. If you were born on December 21, your golden birthday took place when you turned 21.