Probability of girls sit together/ separated

  • Thread starter Thread starter desmond iking
  • Start date Start date
  • Tags Tags
    Probability
Click For Summary
SUMMARY

The discussion focuses on calculating the arrangements of 6 boys and 4 girls sitting in a row, specifically addressing two scenarios: (i) when all girls sit together and (ii) when all girls are separated by boys. The correct calculation for scenario (i) is established as 4! x 7! = 120960. For scenario (ii), the total arrangements are not simply 10! - 120960, as this method incorrectly includes arrangements where girls are adjacent. The correct answer for scenario (ii) is 604800, which accounts for the requirement that no two girls sit next to each other.

PREREQUISITES
  • Understanding of combinatorial mathematics
  • Familiarity with factorial notation and calculations
  • Knowledge of probability concepts
  • Basic principles of permutations and arrangements
NEXT STEPS
  • Study combinatorial arrangements involving restrictions on seating, such as "no two adjacent" conditions
  • Learn about advanced probability techniques in combinatorial contexts
  • Explore the concept of permutations with indistinguishable objects
  • Review factorial calculations and their applications in probability problems
USEFUL FOR

Students studying combinatorial mathematics, educators teaching probability concepts, and anyone interested in solving arrangement problems in discrete mathematics.

desmond iking
Messages
284
Reaction score
2

Homework Statement



Ten Students sit in a row. Find the probability of 6 boys and 4 girls can be arranged if (i) all girls are side by side?
(ii) all girls are separated by boys


Homework Equations





The Attempt at a Solution



my working for part i is 4!x7!=120960

for part ii, why can't i just take 10! -120960=3507840 ? the ans given is 604800
 
Physics news on Phys.org
Part (i) looks OK to me. (7 possible positions for the first girl, 6! ways to order the boys in the remaining positions). If you take 10! minus the result of part (i), what you find is just the number of ways to not have four girls in a row. This includes e.g. gggbgbbbbb which has three girls next to each other, but the problem is asking for arrangements like gbgbbgbgbb, where no two girls are next to each other.
 
Last edited:
Your question "Find the probability of 6 boys and 4 girls can be arranged" doesn't really make sense. From what you do, it appears that the question was really "Find the number of different ways 6 boys and 4 girls can be arranged".
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 9 ·
Replies
9
Views
4K