Time for the Monday Math Quiz!
Here's what's on the menu for the Monday Math Quizzine:
How many randomly selected people have to be in a room before it's more likely than not that two of them share the same birth date. (day and month)
In other words, when are the odds of two people in the room having the same birthday greater than 50-50. The number may surprise you! Assume 365 days per year, ignoring February 29th. (my apologies to you leap-year babies out there)
Thanks and have fun!
(Hint: It's less than 182 people)
How many randomly selected people have to be in a room before it's more likely than not that two of them share the same birth date. (day and month)
In other words, when are the odds of two people in the room having the same birthday greater than 50-50. The number may surprise you! Assume 365 days per year, ignoring February 29th. (my apologies to you leap-year babies out there)
Thanks and have fun!
(Hint: It's less than 182 people)
posted by dewdew @ 7/25/2005 11:53:00 AM
4 Comments:
At July 27, 2005 12:36 PM,
Grend31 said…
Math is hard.
I have no idea.
Guess: 181 people.
At July 28, 2005 9:44 PM,
Dan said…
20 people, right? That makes the probability *counts on fingers, toes, and leg hairs* 190/365?
Did I do that right? (I'm an English teacher, so I'm going to gloat for months if I'm right about this.)
At July 28, 2005 11:05 PM,
Dan said…
Damn it. I just looked up the answer online and discovered it to be slightly greater than my answer.
Oh well: I'll settle for being closer than Grend31.
At July 29, 2005 11:24 AM,
dewdew said…
I am going grant Mr. K the win on this one, for the attempt and for having the general concept. Mr. K receives the prestigious Price is Right award for being the closest without going over, but I won't tell the math teachers if you won't. Even if you don't get the exact answer, devising a way to solve the problem is the important part of math.
The answer is: 23
If you have a room with 23 or more people, chances are better than 50% that two people in the room will have the same birth date. Of course, you could have a room with hundreds of people in it and nobody shares a birthday, but we are talking about probabilities here.
Try it next time you are in a group of 20 or more.
Thanks for playing!
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