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
Basic Concepts of Probability
Problem 5.1.18a
Textbook Question
Lottery. In Exercises 15–20, refer to the accompanying table, which describes probabilities for the California Daily 4 lottery. The player selects four digits with repetition allowed, and the random variable x is the number of digits that match those in the same order that they are drawn (for a “straight” bet).

Using Probabilities for Significant Events
a. Find the probability of getting exactly 2 matches.

1
Step 1: Understand the problem. The question asks for the probability of getting exactly 2 matches in the California Daily 4 lottery. The table provided lists the probabilities for different numbers of matching digits (x).
Step 2: Locate the relevant probability in the table. From the table, the probability of getting exactly 2 matches corresponds to P(x = 2).
Step 3: Identify the value of P(x = 2) from the table. According to the table, P(x = 2) is listed as 0.049.
Step 4: Interpret the result. This means that the probability of getting exactly 2 matches in the California Daily 4 lottery is 0.049, or 4.9%.
Step 5: Conclude the solution. The probability value is directly obtained from the table, and no further calculations are necessary for this problem.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Probability Distribution
A probability distribution describes how the probabilities of a random variable are distributed across its possible values. In this case, the random variable x represents the number of matching digits in the lottery, and the table provides the probabilities for each possible outcome (0 to 4 matches). Understanding this distribution is essential for calculating specific probabilities, such as the likelihood of getting exactly 2 matches.
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Random Variable
A random variable is a numerical outcome of a random phenomenon. In the context of the lottery, the random variable x quantifies the number of digits that match the drawn numbers in the correct order. Recognizing how random variables operate helps in analyzing the probabilities associated with different outcomes, which is crucial for solving the given problem.
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Calculating Probabilities
Calculating probabilities involves determining the likelihood of a specific event occurring based on a probability distribution. For this question, to find the probability of getting exactly 2 matches, one would refer to the provided table and identify the corresponding probability value, which is 0.049. This process is fundamental in statistics for making informed predictions and decisions based on random events.
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