Happy Birthday! (3 Viewers)

[Byrone]

Happy Birthday Rehanint: Man i wish i was there to celebrate with you,21st celebrations are pretty gruesome.

 

Buy on AliExpress.com

[icemaη]

A birthday question: At the moment there are 33 online users in this forum. What's the chance for at least one pair to share their birthdays? More than 50% or less than it?

NOTE: I'll donate 100,000 vcash to the one who could find the right answer being justified by giving reasons

11.8%

 

[Alen]

A birthday question: At the moment there are 33 online users in this forum. What's the chance for at least one pair to share their birthdays? More than 50% or less than it?

NOTE: I'll donate 100,000 vcash to the one who could find the right answer being justified by giving reasons

Bah, the answer is probably +50% because -50% is so obvious, but i have no idea how could it be more than 50% and how will you come up with +50%.

 

[Alen]

11.8%

Errrr, how?

 

[Dostoevsky]

Oh my God Alen doesn't know the answer.

Quick, call 911!

 

[Alen]

Oh my God Alen doesn't know the answer.

Quick, call 911!

Well, i do have an answer but i don't wanna rush with giving it the way Iceman did

 

[icemaη]

Errrr, how?

Do you honestly think I know the answer?

 

[Dostoevsky]

 

[king Ale]

11.8%

That's 100,000 vcash ffs, don't make fun of it you stupid boy

Bah, the answer is probably +50% because -50% is so obvious, but i have no idea how could it be more than 50% and how will you come up with +50%.

Yea, that's why I asked for the reason. At first glance, -50% seems to be the answer but if you think a bit more, you'll see that it's not that obvious

 

[ĵџvє_вãвγ]

thank god i dont need that money :/ ..***..

 

[icemaη]

Maybe you can give me some :eyebrows:

 

[Dostoevsky]

Yo Ice, I can give you ONE.

 

[Alen]

Yea, that's why I asked for the reason. At first glance, -50% seems to be the answer but if you think a bit more, you'll see that it's not that obvious

You can have 50% chance even with 23 people, and you can surely have 50% with 33 people.

Wanna explanation?

 

[ĵџvє_вãвγ]

Maybe you can give me some :eyebrows:

i need to think about it..***..

 

[Byrone]

Cigdem i need an answer in the what you doing right now thread,no is no an option.

 

[Alen]

If no two share a birthday then the first person can choose a birthday
in 365 ways, the second person in 364 ways, the third in 363 ways, and
so on. If there are n people in the room, the probability that no two
share a birthday is

365 x 364 x 363 x ... x (365-n +1) P(365,n)
---------------------------------- = --------
365^n 365^n

So the probability that two at least share a birthday is:

P(365,n)
1 - --------
365^n​

.........................................................P(365,n)
If this must be >= 0.5 then we require -------- <= 0.5
..........................................................365^n

(Here, P(365,n) is the number of permutations of n things that can be
made from 365 different things)

There is no easy way to solve the equation for n, but with a
calculator which gives permutations and combinations, trial and error
will quickly establish that n must be around 23.

P(365,23)
--------- = 0.4927
365^23

and 1 - 0.4927 = 0.5073

and so 23 people are sufficient to make the probability of a shared
birthday greater than 50%. this means that 33 people are more than enough.


Give me my money

 

[king Ale]

You can have 50% chance even with 23 people, and you can surely have 50% with 33 people.

Wanna explanation?

And the chance for it happening with 50 people will increase to 97%

Sure I want explanation

P.S. You shouldn't have edited your post

 

[Byrone]

Alen you just gave me a massive migraine.

 

[king Ale]

If no two share a birthday then the first person can choose a birthday
in 365 ways, the second person in 364 ways, the third in 363 ways, and
so on. If there are n people in the room, the probability that no two
share a birthday is

365 x 364 x 363 x ... x (365-n +1) P(365,n)
---------------------------------- = --------
365^n 365^n

So the probability that two at least share a birthday is:

P(365,n)
1 - --------
365^n​

P(365,n)
If this must be >= 0.5 then we require -------- <= 0.5
365^n

(Here, P(365,n) is the number of permutations of n things that can be
made from 365 different things)

There is no easy way to solve the equation for n, but with a
calculator which gives permutations and combinations, trial and error
will quickly establish that n must be around 23.

P(365,23)
--------- = 0.4927
365^23

and 1 - 0.4927 = 0.5073

and so 23 people are sufficient to make the probability of a shared
birthday greater than 50%. this means that 33 people are more than enough.


Give me my money

In your face Dusan

 

[Alen]

And the chance for it happening with 50 people will increase to 97%

Sure I want explanation

P.S. You shouldn't have edited your post

I explained. Give me my money now.

Btw, Happy Birthday Rehan