Math Problem Statement

Consider all four-digit numbers that can be made from the digits 0-60-6 (assume that numbers cannot start with 00). What is the probability of choosing a random number from this group that is greater than 50005000? Enter a fraction or round your answer to 44 decimal places, if necessary.

Solution

We are given the digits 0, 6, 0, 6 and must form four-digit numbers, ensuring the first two digits do not form "00". Let's determine how many valid numbers exist and then find how many are greater than 5000.

Step 1: Find Total Valid Numbers

Since we have two occurrences each of the digits 0 and 6, the total distinct four-digit numbers that can be formed is calculated by: 4!2!2!=244=6.\frac{4!}{2!2!} = \frac{24}{4} = 6. Listing all possible numbers:

  • 0066 (invalid, as it starts with 00)
  • 0606
  • 0660
  • 6006
  • 6060
  • 6600

Removing 0066, we are left with 5 valid numbers.

Step 2: Count Numbers Greater Than 5000

To be greater than 5000, the first digit must be 6. The valid numbers starting with 6 are:

  • 6006
  • 6060
  • 6600

There are 3 such numbers.

Step 3: Compute Probability

The probability is: favorable casestotal valid cases=35.\frac{\text{favorable cases}}{\text{total valid cases}} = \frac{3}{5}.

Thus, the final answer is 35\frac{3}{5} or 0.6.


Do you want details on another approach? Here are 5 related questions:

  1. How many four-digit numbers can be formed using the digits {1, 1, 2, 2}?
  2. What is the probability of picking a number greater than 4000 from the set {2, 2, 4, 4}?
  3. How would the probability change if we added the digit 9 to our set?
  4. How do we calculate permutations of numbers with repeating digits?
  5. How can we generalize this method for a different set of digits?

Tip: When dealing with permutations of digits with repetition, always use the formula n!r1!r2!...\frac{n!}{r_1!r_2!...} to account for duplicates.

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Math Problem Analysis

Mathematical Concepts

Permutations
Probability
Combinatorics

Formulas

n! / (r1! * r2! * ...)
P(favorable cases) = favorable cases / total cases

Theorems

Permutation with repetition
Basic probability theorem

Suitable Grade Level

Grades 9-12