ZIP Code If you randomly select five digits, each between 0 and 9, with repetition allowed, what is the probability you will get the author’s ZIP code?
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 53m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample2h 19m
- 10. Hypothesis Testing for Two Samples3h 22m
- 11. Correlation1h 6m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
4. Probability
Counting
Problem 4.4.29a
Textbook Question
Mega Millions As of this writing, the Mega Millions lottery is run in 44 states. Winning the jackpot requires that you select the correct five different numbers from 1 to 70 and, in a separate drawing, you must also select the correct single number from 1 to 25.
a. Find the probability of winning the jackpot.

1
Step 1: Understand the problem. To win the Mega Millions jackpot, you must correctly select 5 different numbers from a pool of 70 numbers and 1 additional number (called the Mega Ball) from a separate pool of 25 numbers. The probability of winning is the reciprocal of the total number of possible combinations.
Step 2: Calculate the number of ways to choose 5 numbers from 70. Use the combination formula: C(n, k) = n! / [k!(n-k)!], where n is the total number of items, k is the number of items to choose, and '!' denotes factorial. Here, n = 70 and k = 5. Substitute these values into the formula: C(70, 5) = 70! / [5!(70-5)!].
Step 3: Calculate the number of ways to choose 1 number from 25. Since this is a single choice, the number of ways is simply 25.
Step 4: Multiply the results from Step 2 and Step 3 to find the total number of possible outcomes. The total number of outcomes is given by: Total Outcomes = C(70, 5) × 25.
Step 5: Find the probability of winning the jackpot. The probability is the reciprocal of the total number of outcomes calculated in Step 4. Probability = 1 / (C(70, 5) × 25).

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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 the context of lotteries, it quantifies the chance of winning based on the total number of possible outcomes. For example, if there are 70 numbers to choose from and you need to select 5, the probability of selecting the correct combination is calculated using combinatorial methods.
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Introduction to Probability
Combinations
Combinations refer to the selection of items from a larger set where the order does not matter. In the Mega Millions lottery, you need to choose 5 different numbers from a pool of 70. The number of ways to choose these numbers is calculated using the combination formula, which is crucial for determining the total number of possible winning combinations.
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Combinations
Independent Events
Independent events are those whose outcomes do not affect each other. In the Mega Millions lottery, the selection of the five numbers and the selection of the single number are independent events. This means that the probability of winning the jackpot is the product of the probabilities of each event occurring, which is essential for calculating the overall probability of winning.
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Probability of Multiple Independent Events
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