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
5. Binomial Distribution & Discrete Random Variables
Discrete Random Variables
Problem 4.1.25
Textbook Question
Determining a Missing Probability In Exercises 25 and 26, determine the missing probability for the probability distribution.


1
Step 1: Recall that for a probability distribution, the sum of all probabilities must equal 1. This is a fundamental property of probability distributions.
Step 2: Write the equation to represent the sum of probabilities: \( P(0) + P(1) + P(2) + P(3) + P(4) = 1 \). Substitute the known values: \( 0.06 + 0.12 + 0.18 + P(3) + 0.30 = 1 \).
Step 3: Combine the known probabilities: \( 0.06 + 0.12 + 0.18 + 0.30 = 0.66 \). This simplifies the equation to \( 0.66 + P(3) = 1 \).
Step 4: Solve for \( P(3) \) by subtracting \( 0.66 \) from both sides: \( P(3) = 1 - 0.66 \).
Step 5: Verify that the sum of all probabilities equals 1 after finding \( P(3) \). This ensures the distribution is valid.

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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 are distributed over the values of a random variable. For discrete random variables, it lists each possible value and its corresponding probability, ensuring that the sum of all probabilities equals 1. Understanding this concept is crucial for determining any missing probabilities in a given distribution.
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Calculating Probabilities in a Binomial Distribution
Sum of Probabilities
In a valid probability distribution, the sum of all probabilities must equal 1. This principle is essential for solving problems involving missing probabilities, as it allows us to set up an equation where the unknown probability can be calculated by subtracting the sum of known probabilities from 1.
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Complementary Events
Complementary events are pairs of outcomes in a probability space that cover all possible outcomes. In the context of probability distributions, if we know the probabilities of certain outcomes, we can find the probability of the missing outcome by recognizing that it is the complement of the sum of the known probabilities. This concept aids in efficiently determining missing values.
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