Math Problem Statement

A company has its employees choose a password which consists of 9 characters: 3 letters, followed by 2 symbols, followed by 4 digits. There are a total of 11 symbols that the employees can choose from. Letters, symbols and digits can be repeated. How many possible passwords are there?

Solution

To find the total number of possible passwords, we will calculate the number of choices for each component of the password (letters, symbols, and digits), and then multiply these together, since each component is chosen independently.

Password structure:

The password consists of:

  • 3 letters
  • 2 symbols
  • 4 digits

Step 1: Number of choices for the letters

The total number of letters in the English alphabet is 26. Since letters can be repeated, for each of the 3 positions we have 26 choices.

Thus, the total number of ways to choose 3 letters is: 26×26×26=263=17,57626 \times 26 \times 26 = 26^3 = 17,576

Step 2: Number of choices for the symbols

There are 11 symbols to choose from, and since symbols can be repeated, for each of the 2 positions we have 11 choices.

Thus, the total number of ways to choose 2 symbols is: 11×11=112=12111 \times 11 = 11^2 = 121

Step 3: Number of choices for the digits

There are 10 digits (0 through 9), and since digits can be repeated, for each of the 4 positions we have 10 choices.

Thus, the total number of ways to choose 4 digits is: 10×10×10×10=104=10,00010 \times 10 \times 10 \times 10 = 10^4 = 10,000

Step 4: Total number of possible passwords

Now, multiply the number of choices for each part together: 263×112×104=17,576×121×10,00026^3 \times 11^2 \times 10^4 = 17,576 \times 121 \times 10,000

Calculating: 17,576×121=2,127,69617,576 \times 121 = 2,127,696 2,127,696×10,000=21,276,960,0002,127,696 \times 10,000 = 21,276,960,000

Thus, the total number of possible passwords is: 21,276,960,000\boxed{21,276,960,000}

This is the total number of distinct passwords the employees can create under these conditions.

Would you like more details or have any questions?

Related Questions:

  1. What if the symbols couldn't be repeated? How would that change the answer?
  2. What if the letters couldn't be repeated? How would that affect the result?
  3. How many possible passwords are there if the structure of the password is reversed (digits, symbols, letters)?
  4. What if the password had 4 letters, 3 symbols, and 2 digits instead?
  5. How does the total number of possible passwords change if the company adds 2 more symbols to the list?

Tip:

When calculating combinations or permutations, remember that if repetition is allowed, the number of options remains the same for each position; if not, the number of options decreases for each subsequent choice.

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Math Problem Analysis

Mathematical Concepts

Combinatorics
Counting Principle
Permutations with Repetition

Formulas

Total possible combinations = (choices for letters) * (choices for symbols) * (choices for digits)
Choices for letters = 26^3
Choices for symbols = 11^2
Choices for digits = 10^4

Theorems

Fundamental Counting Principle

Suitable Grade Level

Grades 10-12