Incredibly, this week it's the 10th anniversary of the Charles
Fudgemuffin blog! I've had some significant milestones along the way (such as reaching half a million page views a couple of years ago), but when I started the blog I never imagined I'd still be waffling on each week after ten years!
Anyway, in recognition of my 'birthday', this week's blog post features a birthday themed multiple choice statistical dilemma...
If two people are in the same room, there is a 1 in 365 chance of them sharing the same birthday, or a 0.27% chance.
If 366 people are in the same room, there is a 100% chance that at least two of them will share the same birthday.1
So the question is, how many people would need to be in the room for there to be a 50% chance or greater that at least two people will share a birthday?
A) 23 people
B) 46 people
C) 92 people
D) 183 people
Scroll down the page for the answer...
Answer: The answer is, perhaps rather surprisingly, as low as only 23 people! As implausible as it sounds, with 23 people in the room there is a 50.7% chance that at least two of those people will share a birthday.
A
common wrong answer is 183 people. This is the number of people you
would need for there to be a greater than 50% chance that someone would
share your birthday (if you were one of the people in the room), but for any pair of people to share a
birthday you only need 23 people.
With 30 people the chance of a shared birthday increases to 70.6%, with 70 people there's a 99.9% chance of a shared birthday, and with 100 people there's a 99.99997% chance of a shared birthday!
So by similar logic, if 100 people read this blog post2, there's a 99.99997% chance that two or more of those readers will share a birthday.
So with that in mind, happy birthday to anyone who shares their birthday this week with the Charles Fudgemuffin blog!
You can find more birthday related discussion below:
10 happy birthday messages!
- - - - - - - - - -
1 Unless one of them was born on February 29th on a leap year and everyone else was born on different calendar days, but the chances of that happening are statistically negligible.
2 At the time of writing the Charles Fudgemuffin blog has had an average of around 60,000 page views per year, so with 530 published blog posts that works out at approximately 113 readers each year for each blog post.
Anyway, in recognition of my 'birthday', this week's blog post features a birthday themed multiple choice statistical dilemma...
 |
| Happy Birthday! ...but to how many people? |
Birthday conundrum
If two people are in the same room, there is a 1 in 365 chance of them sharing the same birthday, or a 0.27% chance.
If 366 people are in the same room, there is a 100% chance that at least two of them will share the same birthday.1
So the question is, how many people would need to be in the room for there to be a 50% chance or greater that at least two people will share a birthday?
A) 23 people
B) 46 people
C) 92 people
D) 183 people
Scroll down the page for the answer...
Answer: The answer is, perhaps rather surprisingly, as low as only 23 people! As implausible as it sounds, with 23 people in the room there is a 50.7% chance that at least two of those people will share a birthday.
 |
| Happy birthday themed wrapping paper to wrap up a birthday themed blog post. |
With 30 people the chance of a shared birthday increases to 70.6%, with 70 people there's a 99.9% chance of a shared birthday, and with 100 people there's a 99.99997% chance of a shared birthday!
So by similar logic, if 100 people read this blog post2, there's a 99.99997% chance that two or more of those readers will share a birthday.
So with that in mind, happy birthday to anyone who shares their birthday this week with the Charles Fudgemuffin blog!
You can find more birthday related discussion below:
10 happy birthday messages!
- - - - - - - - - -
1 Unless one of them was born on February 29th on a leap year and everyone else was born on different calendar days, but the chances of that happening are statistically negligible.
2 At the time of writing the Charles Fudgemuffin blog has had an average of around 60,000 page views per year, so with 530 published blog posts that works out at approximately 113 readers each year for each blog post.
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