Pigeohole principle - rolling die

In summary, for this problem, we need to throw a single die at least 7 times to get the same score at least twice, at least 13 times to get the same score at least three times, and at least 6(n-1)+1 times to get the same score at least n times, where n is greater than or equal to 4.
  • #1
jwxie
281
0
How many times must we roll a single die in order to get the same score:
a) at least twice?
b) at least three times?
c) at least n times? for n >= 4

Well I know that P.P says that for m objects, and n boxes, where m > n, there must be one box of n that contains at least two or more objects.

It seems simple, but the application is not.

So for the given problem, like a
There are 6 sides for a single die. And I thought I should do 6^2, since we want to the get the same number at least twice.

I get really stuck at solving this. Can you guys kindly guide me through?

Thanks,
 
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  • #2
Well, the die has six different faces. Do you really need to throw it 62 times to get the same result twice? Think of the different faces as the "holes" and the each throw's score as the "pigeons".
 
  • #3
Okay, in order to get one hole get two pigeons, we need n holes, and n+1 pigeons, so for (a) we need 7, where n = 6.

to get three pigeons in one hole, and we still have 6 (n) holes, i thought we just need another pigeons, total of 8 pigeons, but the answer key said 13. how come?

thanks jsuarez
 
  • #4
we still have 6 (n) holes, i thought we just need another pigeons, total of 8 pigeons

No, for all questions you have just six "holes" (the faces), but the number of "pigeons" (each pigeon is the score at each throw) increases.

So for the second (and third) questions, just apply the same reasoning that you applied on the first. You should be able to see that 8 doesn't work; just look at the following eight (possible) scores: 1 4 3 2 4 2 1 6

So, how many throws do you need for the same score to appear at least three times?
 
  • #5
JSuarez said:
No, for all questions you have just six "holes" (the faces), but the number of "pigeons" (each pigeon is the score at each throw) increases.

So for the second (and third) questions, just apply the same reasoning that you applied on the first. You should be able to see that 8 doesn't work; just look at the following eight (possible) scores: 1 4 3 2 4 2 1 6

So, how many throws do you need for the same score to appear at least three times?

oh right. in order to get another one for the one that has two already, we need another round (which means 6 more)

so the whole process grows by 6(n-1) +1
 
  • #6
Yes.
 

What is the Pigeonhole Principle?

The Pigeonhole Principle, also known as the Dirichlet's box principle, states that if n pigeons are placed into m boxes, with n > m, then at least one box must contain more than one pigeon.

How does the Pigeonhole Principle apply to rolling a die?

When rolling a die, there are 6 possible outcomes (1, 2, 3, 4, 5, 6) and only 5 possible pigeonholes (each side of the die). Therefore, at least one number must appear on multiple sides of the die, fulfilling the conditions of the Pigeonhole Principle.

What is the significance of the Pigeonhole Principle in probability?

The Pigeonhole Principle is often used in probability to prove the existence of certain outcomes. It can be applied to show that in a set of random events, there is a high likelihood of at least one outcome occurring more than once.

How does the Pigeonhole Principle relate to the concept of randomness?

The Pigeonhole Principle challenges the idea of true randomness by showing that in a set of possible outcomes, some outcomes are more likely to occur multiple times than others. This suggests that true randomness may not exist in certain scenarios.

Can the Pigeonhole Principle be applied to real-life situations?

Yes, the Pigeonhole Principle can be applied to various real-life scenarios, such as organizing items into categories, scheduling appointments, and even in the field of computer science. It is a useful tool for understanding patterns and predicting outcomes.

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