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 4.1.17
Textbook Question
In Exercises 13–20, express the indicated degree of likelihood as a probability value between 0 and 1.
Randomness When using a computer to randomly generate the last digit of a phone number to be called for a survey, there is 1 chance in 10 that the last digit is zero

1
Understand the problem: The likelihood of an event is expressed as a probability, which is a value between 0 and 1. Here, the event is the last digit of a phone number being zero, and the given likelihood is '1 chance in 10.'
Recall the formula for probability: \( P(E) = \frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}} \).
Identify the favorable outcomes: In this case, the favorable outcome is the last digit being zero, which is 1 outcome.
Identify the total possible outcomes: Since the last digit of a phone number can be any digit from 0 to 9, there are 10 possible outcomes in total.
Substitute the values into the formula: \( P(E) = \frac{1}{10} \). This fraction represents the probability of the last digit being zero.

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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 value between 0 and 1. A probability of 0 indicates that the event cannot happen, while a probability of 1 indicates certainty that the event will occur. In this context, the probability of the last digit being zero is calculated based on the total number of possible outcomes.
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Randomness
Randomness refers to the lack of pattern or predictability in events. In statistical terms, a random process produces outcomes that are not influenced by previous outcomes. When generating the last digit of a phone number randomly, each digit from 0 to 9 has an equal chance of being selected, ensuring that the selection is unbiased and truly random.
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Sample Space
The sample space is the set of all possible outcomes of a random experiment. For the last digit of a phone number, the sample space consists of the digits 0 through 9, totaling 10 possible outcomes. Understanding the sample space is crucial for calculating probabilities, as it provides the basis for determining the likelihood of specific events occurring within that space.
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