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Counting Principles and Permutations in Probability

스터디 가이드 - 스마트 노트

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Section 3.4: Additional Topics in Probability and Counting

Section 3.4 Objectives

This section introduces advanced counting techniques essential for probability and statistics. The main objectives are:

  • To determine the number of ways a group of objects can be arranged in order.

  • To find the number of ways to choose several objects from a group without regard to order.

  • To use counting principles to calculate probabilities.

Permutations

Definition and Formula

A permutation is an ordered arrangement of objects. The order in which the objects are arranged is important. The number of different permutations of n distinct objects is given by the factorial of n:

  • Factorial: The product of all positive integers up to n, denoted as n!

The formula for the number of permutations of n objects is:

Example: Finding the Number of Permutations of n Objects

Problem: The objective of a 9 x 9 Sudoku number puzzle is to fill the grid so that each row, each column, and each 3 x 3 grid contains the digits 1 to 9. How many different ways can the first row of a blank 9 x 9 Sudoku grid be filled?

Solution: The number of permutations is .

Sudoku permutation example and formula

Example Application: This calculation is used to determine the number of possible arrangements for the first row in Sudoku, illustrating the concept of permutations in a real-world puzzle.

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