Solve Pigeon Hole Theory Problems

  • Context: MHB 
  • Thread starter Thread starter JProgrammer
  • Start date Start date
  • Tags Tags
    Hole Theory
Click For Summary
SUMMARY

The discussion centers on applying the generalized pigeonhole principle to solve problems involving sock selection. For part (a), the conclusion is that a man must pull out 4 socks to guarantee at least one matching pair, as there are 3 colors of socks available. For part (b), to ensure he gets a blue pair, he must pull out 23 socks, accounting for the worst-case scenario of selecting all black and brown socks first before reaching the blue ones.

PREREQUISITES
  • Understanding of the generalized pigeonhole principle
  • Basic combinatorial mathematics
  • Problem-solving skills in probability theory
  • Familiarity with worst-case scenario analysis
NEXT STEPS
  • Study advanced applications of the pigeonhole principle in combinatorics
  • Explore probability theory related to selection problems
  • Learn about worst-case analysis in mathematical problems
  • Practice solving similar problems involving combinatorial logic
USEFUL FOR

Mathematicians, educators, students in combinatorics, and anyone interested in probability theory and problem-solving strategies.

JProgrammer
Messages
20
Reaction score
0
So I need to use pigeon hole theory to solve these problems:

3. A man has 10 black socks, 11 brown socks and 12 blue socks in a drawer. He isn’t a morning person, so every morning he just reaches in and pulls out socks until he gets two that match.
a. Use the generalized pigeonhole principle to determine how many socks he has to pull out before he gets two of the same color.
b. How many must he pull out to be certain of getting a blue pair?

a. I am thinking that the pigeons are the colors and the pigeon holes are the number of socks that are pulled out. If that were the case, I believe the answer would be 5. But the number of each color of socks is not the same. So am I right about this or do I need to take into consideration the different amount of socks?

b. The most I could go with this problem is that since there are 33 socks total and 12 of those socks are blue, the pigeon hold theory would yield 3. My question is: where would I go from here?
 
Physics news on Phys.org
JProgrammer said:
So I need to use pigeon hole theory to solve these problems:

3. A man has 10 black socks, 11 brown socks and 12 blue socks in a drawer. He isn’t a morning person, so every morning he just reaches in and pulls out socks until he gets two that match.
a. Use the generalized pigeonhole principle to determine how many socks he has to pull out before he gets two of the same color.
b. How many must he pull out to be certain of getting a blue pair?

a. I am thinking that the pigeons are the colors and the pigeon holes are the number of socks that are pulled out. If that were the case, I believe the answer would be 5. But the number of each color of socks is not the same. So am I right about this or do I need to take into consideration the different amount of socks?

b. The most I could go with this problem is that since there are 33 socks total and 12 of those socks are blue, the pigeon hold theory would yield 3. My question is: where would I go from here?

Hey JProgrammer! ;)

a. We're talking about a bad day here.
Worst case scenario is that he pulls out a black sock, a brown sock, and a blue sock.
After that there is no choice anymore - he will pull out one of the colors he already has.
So that means that with 4 socks he will get a pair.
That is, the pidgeon hole theory says that if you pull 4 items when there are only 3 choices, you'll get at least 2 identical choices.

b. Same thing - a bad day.
He can pick 10 black socks and 11 brown socks before getting to blue socks.
And then he still has to pull 2 blue socks.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 3 ·
Replies
3
Views
946
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 19 ·
Replies
19
Views
4K