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Jul 20, 2024
Jul 19, 2024
 #2
avatar+868 
0

Given that Catherine rolls a standard 6-sided die six times and the product of her rolls is 600, we need to determine how many different sequences of rolls could result in this product. 

 

Firstly, we factorize 600 into its prime factors:
\[ 600 = 2^3 \times 3 \times 5^2 \]

 

The numbers on a 6-sided die are 1, 2, 3, 4, 5, and 6. We need to express each of these numbers in terms of their prime factorizations:


- \(1 = 1\)
- \(2 = 2\)
- \(3 = 3\)
- \(4 = 2^2\)
- \(5 = 5\)
- \(6 = 2 \times 3\)

 

The product of these rolls must equate to \(2^3 \times 3 \times 5^2\). Since each roll can only be 1, 2, 3, 4, 5, or 6, we must distribute the prime factors accordingly among the six rolls.

 

### Step 1: Distribute the Prime Factors


Each roll will contribute to the overall prime factorization of 600. We identify which numbers can be used and their respective contributions:


- \(2\): contributes \(2\)
- \(3\): contributes \(3\)
- \(4\): contributes \(2^2\)
- \(5\): contributes \(5\)
- \(6\): contributes \(2 \times 3\)

 

### Step 2: Determine Possible Rolls


To satisfy the factorization \(2^3 \times 3 \times 5^2\) with six rolls:


- We need three 2's.
- We need one 3.
- We need two 5's.

 

Possible combinations of rolls can be:


- 2 can be contributed by 2, 4 (as \(2^2\)), or 6 (as \(2\)).
- 3 can be contributed by 3 or 6 (as \(3\)).
- 5 can be contributed by 5.

 

### Step 3: Identify Suitable Rolls


We need to select rolls that collectively provide the correct number of prime factors:


- \(2\) appears in rolls: \(2, 4, 6\).
- \(3\) appears in rolls: \(3, 6\).
- \(5\) appears in rolls: \(5\).

 

### Step 4: Determine Combinations


Let's break down how we can achieve the required distribution:


- \(2^3\) can be achieved by: 
  - (2, 2, 2)
  - (4, 2)
  - (4, 4)
  - (2, 6)
  - (6, 6)
  
- \(3\) must be from: 
  - (3)
  - (6)
  
- \(5^2\) must be from: 
  - (5, 5)

 

The valid combinations, ensuring the product is exactly 600, and considering the requirement for six rolls, are:


\[ (2, 2, 2, 3, 5, 5) \]

 

### Step 5: Counting Permutations


The total number of distinct sequences for the combination (2, 2, 2, 3, 5, 5) is given by counting permutations of these 6 items where the 2's and 5's are repeated:


\[ \frac{6!}{3! \cdot 2!} = \frac{720}{6 \cdot 2} = 60 \]

 

Therefore, there are 60 different sequences of rolls that produce the product 600.

 

Thus, the number of different sequences of rolls that could result in the product being 600 is:


\[ \boxed{60} \]

Jul 19, 2024
 #2
avatar+820 
0

To solve the problem of finding the number of ways the numbers 1 through 5 can be arranged into the five boxes so that the inequalities \(\_ < \_ > \_ < \_ > \_\) hold, we need to carefully consider the pattern and constraints.

 

Let's break it down step by step:

 

1. **Pattern Analysis:**


   - The sequence alternates between increasing and decreasing.


   - If we let the positions be labeled as \(a < b > c < d > e\), we need to ensure that each set of inequalities is satisfied.

 

2. **Key Points:**


   - The first number must be less than the second number.


   - The second number must be greater than the third number.


   - The third number must be less than the fourth number.


   - The fourth number must be greater than the fifth number.

 

3. **Counting Valid Sequences:**


   - There are a total of 5! (120) possible permutations of the numbers 1 through 5.


   - We need to determine how many of these permutations satisfy the given inequalities.

 

One way to approach this problem is to use a systematic method to generate valid sequences, but a more efficient way is to realize that this problem is a known combinatorial problem.

 

### Generating Function Approach (Optional):

 

This problem can also be solved using generating functions and other combinatorial techniques, but for simplicity, let's use a direct combinatorial argument.

 

### Direct Counting:

 

Instead of listing all permutations, we can use a combinatorial argument based on symmetry and known results in permutations and inequalities.

For a permutation of \(n\) elements satisfying a specific pattern of inequalities like this, it can be shown that the number of valid permutations is given by:

 

\[ \frac{(n-1)!}{(k-1)! \cdot (n-k-1)!} \]

 

where \(k\) is the number of ascents (increasing steps) in the permutation.

 

For the pattern \(_ < _ > _ < _ > _\), there are 2 ascents and 2 descents in the sequence.

 

Therefore, the number of valid permutations is:

 

\[ \frac{4!}{1! \cdot 1! \cdot 2!} = \frac{24}{2} = 12 \]

 

Thus, there are 12 valid ways to arrange the numbers 1 through 5 into the five boxes to satisfy the given inequalities.

Jul 19, 2024
 #1
avatar+8 
+1
Jul 19, 2024

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