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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
All textbooksLarson 8th EditionCh. 3 - ProbabilityProblem 3.R.51
Chapter 3, Problem 3.R.51

In Exercises 49-53, use counting principles to find the probability.
51. A shipment of 200 calculators contains 3 defective units. What is the probability that a sample of three calculators will have
c. at least one defective calculator?

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1
Step 1: Understand the problem. We are tasked with finding the probability that a sample of three calculators, chosen from a shipment of 200 calculators (3 of which are defective), contains at least one defective calculator. This is a complementary probability problem, so we will first calculate the probability of the complement event (no defective calculators in the sample) and subtract it from 1.
Step 2: Define the complement event. The complement event is that all three calculators in the sample are non-defective. There are 200 calculators in total, and 200 - 3 = 197 of them are non-defective. The probability of selecting only non-defective calculators can be calculated using combinations.
Step 3: Use combinations to calculate the total number of ways to choose 3 calculators from the shipment. The total number of ways to choose 3 calculators from 200 is given by the combination formula: C(n, r) = n! / [(r!)(n - r)!]. Here, n = 200 and r = 3. Compute C(200, 3).
Step 4: Use combinations to calculate the number of ways to choose 3 non-defective calculators from the 197 non-defective ones. This is given by C(197, 3), where n = 197 and r = 3. Compute C(197, 3).
Step 5: Calculate the probability of the complement event (no defective calculators) by dividing the number of ways to choose 3 non-defective calculators by the total number of ways to choose 3 calculators: P(no defective) = C(197, 3) / C(200, 3). Finally, subtract this probability from 1 to find the probability of at least one defective calculator: P(at least one defective) = 1 - P(no defective).

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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 an event will occur, expressed as a number between 0 and 1. In this context, it quantifies the chance of selecting at least one defective calculator from a sample of three. Understanding how to calculate probability is essential for solving problems involving random selections from a finite population.
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Introduction to Probability

Counting Principles

Counting principles, such as combinations and permutations, are mathematical techniques used to determine the number of ways to select items from a larger set. In this problem, combinations are particularly relevant as we need to calculate the different ways to choose calculators from the shipment, which helps in determining the total outcomes for the probability calculation.
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Fundamental Counting Principle

Complement Rule

The complement rule in probability states that the probability of an event occurring is equal to 1 minus the probability of it not occurring. In this case, to find the probability of selecting at least one defective calculator, it is often easier to first calculate the probability of selecting none and then subtracting that from 1. This approach simplifies the calculation process.
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Complementary Events
Related Practice
Textbook Question

In Exercises 45-48, use combinations and permutations.

46. Five players on a basketball team must each choose one of the five players on the opposing team to defend. In how many ways can the players choose their defensive assignments?

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Textbook Question

6. A shipment of 250 netbooks contains 3 defective units. Determine how many ways a vending company can buy three of these units and receive

c. at least one good unit.

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Textbook Question

"In Exercises 1-4, identify the sample space of the probability experiment and determine the number of outcomes in the event. Draw a tree diagram when appropriate.

1. Experiment: Tossing four coins

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Textbook Question

"In Exercises 1-4, identify the sample space of the probability experiment and determine the number of outcomes in the event. Draw a tree diagram when appropriate.

4. Experiment: Guessing the gender(s) of the three children in a family

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Textbook Question

The table shows the numbers (in thousands) of earned degrees by level in two different fields, conferred in the United States in a recent year. (Source: U.S. National Center for Education Statistics)

A person who earned a degree in the year is randomly selected. Find the probability that the degree earned by the person is a

g. bachelor's degree and the degree is in natural sciences/mathematics.

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Textbook Question

In Exercises 49-53, use counting principles to find the probability.

53. A corporation has six male senior executives and four female senior executives. Four senior executives are chosen at random to attend a technology seminar. What is the

probability of choosing

c. two men and two women?

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