Question 1
How many distinct arrangements can be made using all the letters of the word 'BALL'?
Step-by-Step Solution:
Concept: Permutation with repetition. When some objects are identical, we divide by the factorial of the number of repetitions.
Analysis of 'BALL':
- Total letters: 4
- Some letters are repeated
Formula: n! / (p! × q! × ...)
where p, q, ... are the frequencies of repeated letters
Calculation:
If all letters were distinct: 4! = 24 arrangements
But some letters are repeated, so we have overcounted.
We must divide by 2! for the repeated letters.
Answer = 24 / 2 = 12
Key Principle: Identical objects create duplicate arrangements. We divide by their factorial to remove duplicates.
Why divide?: The repeated letters can be swapped among themselves without creating a new arrangement. We divide to account for this overcounting.
Concept: Permutation with repetition. When some objects are identical, we divide by the factorial of the number of repetitions.
Analysis of 'BALL':
- Total letters: 4
- Some letters are repeated
Formula: n! / (p! × q! × ...)
where p, q, ... are the frequencies of repeated letters
Calculation:
If all letters were distinct: 4! = 24 arrangements
But some letters are repeated, so we have overcounted.
We must divide by 2! for the repeated letters.
Answer = 24 / 2 = 12
Key Principle: Identical objects create duplicate arrangements. We divide by their factorial to remove duplicates.
Why divide?: The repeated letters can be swapped among themselves without creating a new arrangement. We divide to account for this overcounting.