/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 12 Suppose there are 30 people at a... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Suppose there are 30 people at a party. Do you think any two share the same birthday? Let's use the random-number table to simulate the birthdays of the 30 people at the party. Ignoring leap year, let's assume that the year has 365 days. Number the days, with 1 representing January 1,2 representing January 2, and so forth, with 365 representing December 31. Draw a random sample of 30 days (with replacement). These days represent the birthdays of the people at the party. Were any two of the birthdays the same? Compare your results with those obtained by other students in the class. Would you expect the results to be the same or different?

Short Answer

Expert verified
It's likely that at least two people share the same birthday, due to the Birthday Paradox.

Step by step solution

01

Understanding the Problem

We need to determine if at least two people in a group of 30 share the same birthday. To simulate this, we'll randomly assign each of the 30 people a birthday using a number between 1 and 365, representing days of the year.
02

Generate Random Birthdays

Using a random-number table or a computer program that can generate random numbers, assign each of the 30 people a day of the year (numbered 1 to 365). Make sure to generate these numbers with replacement, meaning each number can be drawn more than once.
03

Record Birthdays

Write down the list of 30 randomly generated numbers. Each number represents a person's birthday, from day 1 to day 365. Ensure you keep track of all the numbers drawn.
04

Identify Duplicates

Check your list of 30 birthdays for any duplicates. If two or more numbers in your list are the same, this means at least two people share a birthday.
05

Discuss Results

Compare your results with other classmates who perform the same experiment. Notice if results vary within the class.
06

Analyzing Expectations

Based on probability, there is a high likelihood that two people will share a birthday, known as the Birthday Paradox. The probability that no two people in a group of 30 share a birthday is lower than the probability that at least two do.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Birthday Paradox
The Birthday Paradox might seem counterintuitive at first. You would think that with 365 days in a year, sharing a birthday among just 30 people seems unlikely. However, probability tells us otherwise. Mathematically, the likelihood of two people sharing a birthday increases rapidly with the number of people involved.
The paradox arises because we're not just comparing one person's birthday with another's. Instead, we're comparing every possible pair within the group. For 30 people, this results in a large number of pairs, specifically \((\frac{30 \, \times \, 29}{2}) \, = \, 435\) pairs. This dramatically boosts the chances of finding a shared birthday.
This phenomenon illustrates how human intuition can sometimes misjudge probabilities when large numbers of comparisons are involved. Understanding the birthday paradox highlights the intriguing world of probability and how surprising results can emerge.
Random Number Generation
Random number generation is crucial for simulating scenarios like the Birthday Paradox. In our exercise, we're assigning each person a random number between 1 and 365, simulating their birthday.
Generating a random number can be achieved using statistical tables or computer programs that ensure each day of the year has an equal chance of being selected. This randomness helps mimic real-world situations where each person has an equal probability of being born on any given day, disregarding seasonal birth trends.
It's important to note that in our setup, numbers are drawn with replacement, allowing the same number to be selected more than once, which closely reflects real-life where people can indeed share birthdays. Random number generation is essential in devising realistic simulations and conducting fair experiments.
Simulation
Simulation plays a pivotal role in understanding complex problems like the Birthday Paradox. By creating a model of a real-world situation, we can predict outcomes and analyze probabilities without directly experimenting in real life.
In this context, a simulation was used to replicate a gathering of 30 people, all assigned random birthdays. Conducting a simulation multiple times allows for the observation of patterns and helps estimate probabilities more acutely.
Simulations are favored in many statistical and scientific fields as they provide a risk-free zone where variables can be manipulated without real-world consequences. They can reveal insights that aren't immediately evident from theoretical calculations alone.
Duplicates
In the Birthday Paradox scenario, identifying duplicates among random numbers is key to determining if at least two people share a birthday. Once we've generated a list of random numbers, each representing a potential birthday, we examine these values for repetitions.
When a duplicate is found in the list, it indicates that at least those two individuals share the same day of birth. Finding duplicates is essentially solving the core problem posed by the Birthday Paradox.
This process is simplified by techniques such as sorting the list first or using a data structure, like a set, to efficiently track unique values and quickly identify any repeats. The concept of duplicates is fundamental in probability and emphasizes the importance of correct data handling during experiments.
Statistical Experiment
Conducting a statistical experiment like the one described helps deepen our understanding of probabilities and random events. The experiment is designed to answer a specific question—in this case, whether two people in a group share the same birthday.
After simulating and generating results, we delve into the analysis phase, comparing outcomes with expected probability metrics.
Discussion among peers, as suggested in the exercise, helps highlight how varying initial conditions can influence outcomes and teaches us about variability and confidence in data analysis. Statistical experiments are vital in testing hypotheses in a systematic manner, providing evidential support for theoretical findings.

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Most popular questions from this chapter

Modern Managed Hospitals (MMH) is a national for-profit chain of hospitals. Management wants to survey patients discharged this past year to obtain patient satisfaction profiles. They wish to use a sample of such patients. Several sampling techniques are described below. Categorize each technique as simple random sample, stratified sample, systematic sample, cluster sample, or convenience sample. (a) Obtain a list of patients discharged from all MMH facilities. Divide the patients according to length of hospital stay \((2\) days or less, \(3-7\) days, \(8-14\) days, more than 14 days). Draw simple random samples from each group. (b) Obtain lists of patients discharged from all MMH facilities. Number these patients, and then use a random-number table to obtain the sample. (c) Randomly select some MMH facilitics from each of five geographic regions, and then include all the patients on the discharge lists of the selected hospitals. (d) At the beginning of the year, instruct each MMH facility to survey every 500th patient discharged. (e) Instruct each MMH facility to survey 10 discharged patients this week and send in the results.

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