Table of contents
- 1. Intro to Stats and Collecting Data55m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically1h 45m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables2h 33m
- 6. Normal Distribution and Continuous Random Variables1h 38m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 3m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample1h 1m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
4. Probability
Counting
Problem 3.RE.42
Textbook Question
In Exercises 41-44, perform the indicated calculation.
42. 8P6

1
Step 1: Understand the notation 8P6. This represents a permutation, which is the number of ways to arrange 6 items out of 8 in a specific order. The formula for permutations is given by P(n, r) = n! / (n - r)!, where n is the total number of items, and r is the number of items to arrange.
Step 2: Identify the values of n and r in the problem. Here, n = 8 and r = 6.
Step 3: Substitute the values of n and r into the permutation formula. This gives P(8, 6) = 8! / (8 - 6)!. Simplify the denominator to get P(8, 6) = 8! / 2!.
Step 4: Expand the factorials in the numerator and denominator. Recall that 8! = 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 and 2! = 2 × 1. Cancel out the common terms in the numerator and denominator.
Step 5: Multiply the remaining terms in the numerator after cancellation to compute the result. This will give you the total number of permutations for arranging 6 items out of 8.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Permutations
Permutations refer to the different ways of arranging a set of items where the order matters. The notation nPr represents the number of ways to choose r items from a total of n items, considering the arrangement. For example, if you have 3 letters A, B, and C, the permutations of choosing 2 letters would include AB, AC, BA, BC, CA, and CB.
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Factorial
A factorial, denoted as n!, is the product of all positive integers up to n. It is a fundamental concept in combinatorics, used to calculate permutations and combinations. For instance, 5! equals 5 × 4 × 3 × 2 × 1 = 120. Factorials grow rapidly, making them essential for counting arrangements and selections.
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Calculation of Permutations
The formula for calculating permutations is given by nPr = n! / (n - r)!. This formula allows you to determine the number of ways to arrange r items from a total of n items. In the case of 8P6, you would calculate it as 8! / (8 - 6)! = 8! / 2!, which simplifies the computation by reducing the factorial terms.
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