Probability of person who sit in a circle

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Homework Help Overview

The problem involves arranging a committee of 3 teachers and 4 parents around a round table with 7 seats labeled A to G. Participants are exploring different scenarios for seating arrangements, including cases with and without restrictions.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Some participants discuss the total arrangements without restrictions, while others focus on the scenario where all teachers must sit together. There are attempts to clarify the logic behind the calculations and the arrangement of the groups.

Discussion Status

The discussion includes various interpretations of how to approach the arrangement problem, with some participants questioning the validity of certain calculations and suggesting alternative methods for counting arrangements. There is an ongoing exploration of how to treat the teachers as a single entity versus separate individuals.

Contextual Notes

Participants are working under the constraints of a round table arrangement, which affects the counting of distinct seating arrangements. There is also a focus on the implications of treating groups as blocks versus individuals in the arrangement process.

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Homework Statement



there are 7 seats around a round table, and is labelled form A to G. Find the number of ways a committee of 3 teachers and 4 parents can sit around the table?

(i ) there is no restriction
my ans is 7!=5040

(ii) all teachers must sit together
the ans is 1008. can someone explain part ii please? my wokring is (6!/(3! x 4!) ) x 4! = 120...

Homework Equations





The Attempt at a Solution

 
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desmond iking said:

Homework Statement



there are 7 seats around a round table, and is labelled form A to G. Find the number of ways a committee of 3 teachers and 4 parents can sit around the table?

(i ) there is no restriction
my ans is 7!=5040

(ii) all teachers must sit together
the ans is 1008. can someone explain part ii please? my wokring is (6!/(3! x 4!) ) x 4! = 120...

Homework Equations





The Attempt at a Solution


What's your logic for that working? First count the number of ways to pick a block of 4 adjacent chairs, then multiply by the number of ways you can seat the 4 teachers there and the three parents in the remaining 3 seats.
 
sorry my working should be 3! x 5! = 720 which means i arrange the teacher in 3 ! ways first , then i arrange the whole set of teacher into another 5! ways.
 
desmond iking said:
sorry my working should be 3! x 5! = 720 which means i arrange the teacher in 3 ! ways first , then i arrange the whole set of teacher into another 5! ways.
Guessing here, but I think what you mean is that having fixed the order of the 3 teachers you treat them as a single entity. So now you have four parents and a block of teachers.
That doesn't quite work. Say you put the teacher block 'at' A. Is that at ABC, or GAB or FGA?
Having got the 3! for the block of teachers, think about how to arrange the parents as a block, then how to match the two blocks to the 7 chairs.
 

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