Question 1
Consider 13 marbles: 4 of color 1, 2 of color 2, 2 of color 3, 3 of color 4, 2 of color 5. How many distinct ways can these marbles be arranged in a row?
Step-by-Step Solution:
Concept: Permutations with identical objects. When objects of the same type are indistinguishable, we divide by the factorial of each type's count.
Formula:
$$\frac{n!}{n_1! \cdot n_2! \cdot ... \cdot n_k!}$$
where $n$ is total objects and $n_i$ is the count of type $i$.
Given Data:
- Total objects: 13
- Distribution: Type 1: 4, Type 2: 2, Type 3: 2, Type 4: 3, Type 5: 2
Step 1 - Total arrangements if all were distinct:
13! = 6227020800
Step 2 - Account for identical objects:
13! = 6227020800 / 4! = 24 / 2! = 2 / 2! = 2 / 3! = 6 / 2! = 2
Final Calculation:
= 5405400
Key Principle: Each group of identical objects overcounts by a factor of (count)!. Division corrects this.
Verification: The result is an integer and less than 13! = 6227020800.
Concept: Permutations with identical objects. When objects of the same type are indistinguishable, we divide by the factorial of each type's count.
Formula:
$$\frac{n!}{n_1! \cdot n_2! \cdot ... \cdot n_k!}$$
where $n$ is total objects and $n_i$ is the count of type $i$.
Given Data:
- Total objects: 13
- Distribution: Type 1: 4, Type 2: 2, Type 3: 2, Type 4: 3, Type 5: 2
Step 1 - Total arrangements if all were distinct:
13! = 6227020800
Step 2 - Account for identical objects:
13! = 6227020800 / 4! = 24 / 2! = 2 / 2! = 2 / 3! = 6 / 2! = 2
Final Calculation:
= 5405400
Key Principle: Each group of identical objects overcounts by a factor of (count)!. Division corrects this.
Verification: The result is an integer and less than 13! = 6227020800.