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Ch. 3 - Probability
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook
Chapter 3, Problem 3.4.40

Board of Directors The University of Colorado Board of Directors has 23 members. One member serves as board chair and another serves as vice chair. Given the names of the 23
board members, what is the probability of randomly selecting the name of the chair and the name of the vice chair? (Source: University of Colorado)

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1
Step 1: Understand the problem. We are tasked with finding the probability of randomly selecting one person as the chair and another as the vice chair from a group of 23 members. This is a problem involving combinations and probabilities.
Step 2: Calculate the total number of ways to select the chair and vice chair. Since the selection is ordered (chair first, then vice chair), this is a permutation problem. The number of permutations is given by the formula: P(n, r) = n! / (n - r)!, where n is the total number of members (23) and r is the number of positions to fill (2).
Step 3: Substitute the values into the permutation formula. Using MathML, the formula becomes: n!(n - r)!. Here, n = 23 and r = 2, so the calculation is: 23!(23 - 2)!.
Step 4: Simplify the expression. The factorials simplify to: 23 × 22, because the remaining terms cancel out when dividing 23! by (23 - 2)!.
Step 5: Calculate the probability. Since there is only one specific pair of names that can be selected as the chair and vice chair, the probability is the reciprocal of the total number of permutations. This is given by: P = 1 / (23 × 22).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Probability

Probability is a measure of the likelihood that a particular event will occur, expressed as a number between 0 and 1. In this context, it refers to the chance of randomly selecting specific individuals from a group. The probability of an event can be calculated by dividing the number of favorable outcomes by the total number of possible outcomes.
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Combinations

Combinations refer to the selection of items from a larger set where the order does not matter. In the context of this question, it involves selecting the chair and vice chair from the board members. Understanding combinations is essential for calculating probabilities when the order of selection is irrelevant.
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Combinations

Random Selection

Random selection is a process where each member of a group has an equal chance of being chosen. This concept is crucial for ensuring that the probability calculations are valid, as it assumes that the selection of the chair and vice chair is unbiased and purely based on chance, without any influence from external factors.
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