# Thread: PROBABILITY- extension of the birthday problem

1. ## PROBABILITY- extension of the birthday problem

I'm writing an IB math paper on the birthday paradox... At first, I wanted to answer the question,

How many friends would you have tomato to have a 90+% probability that for everyday of the year, you have at least one friend with a birthday ?
The answer is 2153, (saw off a math/science-y youtube channel) but I have no idea how they came to that, and I need to show the work.

discouraged, I decided to try a different question, "How many people would you need (#n) to reach a probability of 90+% that someone shares you EXACT birthday, including not just the month and day, but also the year and hour.

I know these are really complicated and I've likely bitten off more than I could chew, but is there anyone out there that can help me with either?? I would REALLY appreciate it!

2. Originally Posted by mathluva3141
I'm writing an IB math paper on the birthday paradox... At first, I wanted to answer the question,

How many friends would you have tomato to have a 90+% probability that for everyday of the year, you have at least one friend with a birthday ?
The answer is 2153, (saw off a math/science-y youtube channel) but I have no idea how they came to that, and I need to show the work.

discouraged, I decided to try a different question, "How many people would you need (#n) to reach a probability of 90+% that someone shares you EXACT birthday, including not just the month and day, but also the year and hour.

I know these are really complicated and I've likely bitten off more than I could chew, but is there anyone out there that can help me with either?? I would REALLY appreciate it!

Please share your work with us ...even if you know it is wrong.

If you are stuck at the beginning tell us and we'll start with the definitions.

http://www.freemathhelp.com/forum/announcement.php?f=33