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Harris Interactive conducted a survey for Tylenol PM asking U.S. drivers what they do if they are driving while drowsy. The results were reported in a USA Today Snapshot on January \(18,2005,\) with \(40 \%\) of the respondents saying they "open the windows" to fight off sleep. Suppose that 35 U.S. drivers are interviewed. What is the probability that between 10 and 20 of the drivers will say they "open the windows" to fight off sleep?

Short Answer

Expert verified
The probability that between 10 and 20 of the 35 drivers (inclusive), when surveyed, will say they 'open the windows' to fight off sleep is the sum of the calculated individual probabilities.

Step by step solution

01

Identify Necessary Variables

In this problem, the sample size \(n\) is 35 drivers. The success probability \(p\) in a binomial distribution here is represented by the proportion of drivers who say they 'open the windows', which is \(0.4.\) In this case, 'x', the number of successes, is a range from 10 to 20.
02

Calculate Individual Probabilities

We need to calculate the binomial probability for each value of 'x' within the range 10 to 20. The formula for calculating binomial probability is given as follows: \[ P(X=x) = \binom{n}{x} * p^x * (1-p)^{n-x} \] Where \[\binom{n}{x}\] represents the number of combinations of 'n' items taken 'x' at a time. This could be calculated using the formula: \[\binom{n}{x} = \frac{n!}{x!(n-x)!} \] So, we will plug in the given values into the formula and calculate the probability for each individual number from 10 to 20.
03

Sum of the Probabilities

After calculating the probabilities for each individual number of 'successes' from 10 to 20 inclusive, we will sum up all these probabilities. The result is the wanted probability of getting between 10 and 20 successes (inclusive) when surveying 35 drivers.

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Key Concepts

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

Understanding the Binomial Distribution
Binomial distribution is a cornerstone concept within probability theory, specifically tailored to situations where there are only two outcomes for each trial—commonly referred to as 'success' and 'failure'. In our exercise scenario, the success was a driver saying they 'open the windows' to fight off sleep. This distribution requires three parameters for its complete description: the number of trials (), the probability of success in a single trial (), and the number of successes ().

The binomial distribution formula, , calculates the probability of obtaining exactly successes out of trials. This distribution assumes each trial is independent, meaning the outcome of one trial doesn’t affect the outcome of another. It's important to understand that we're speaking of discrete outcomes, which makes this distribution a go-to tool when dealing with distinct events, as in the case of our exercise.

When tasked with understanding this concept, it's beneficial to explore specific examples with different and values to solidify the theory. One could simulate flipping a coin, where represents the probability of getting heads, which would be 0.5, and the number of flips. The core of binomial distribution exercises often revolves around calculating these probabilities and understanding the behavior of the distribution through its probability mass function (PMF).
Probability Theory Fundamentals
Probability theory allows us to quantify the likelihood of events, spanning from coin tosses to more complex phenomena like the behavior of stock markets. At its heart is the notion that given all possible outcomes of a random experiment, the sum of the probabilities must equal 1. In the context of binomial distribution, probability theory empowers us to compute the chances of a specific number of successes. This is encapsulated in the example provided, where we want to identify the likelihood of 10 to 20 drivers opening the windows.

Probability theory topics, such as random variables, probability distributions, and expectation, are quintessential for interpreting data and predicting outcomes. For instance, a random variable in our exercise () refers to the count of drivers who take a specific action. By leveraging the probability mass function of a binomial distribution, we can calculate individual probabilities and the cumulative effect within a specific range.

This theory also aids in comprehending 'expected value', which for a binomial distribution is simply . It's central for students to visualize probability through the lens of practical examples, reinforcing concepts such as independence of events, the role of combinatorics in calculating probabilities, and the convergence of repeated trials to expected values.
Statistics and Data Analysis
Statistics is the art and science of collecting, analyzing, interpreting, and presenting data. It offers the tools necessary to convert raw data into usable information, which helps in decision making. In the given exercise, statistics play a formidable role when it comes to analyzing survey results and inferencing from a sample to a larger population regarding drowsy drivers that 'open the windows'.

The binomial distribution model is a statistical method to understand and represent the data obtained from binary outcomes. Here, statisticians also analyze the variance and standard deviation of a binomial distribution, which provides insights into the data's dispersion around the expected value.When improving exercises in statistics, one could focus on providing real-world examples, like the Tylenol PM survey, to clearly illustrate statistical theories. Additionally, using visual aids like graphs to explain variability, and reinforcement through practice with varying sample sizes () and probability of successes (), enriches the learning experience.

Moreover, it underscores the importance of robust sampling techniques and the interpretation of results, like understanding the significance of confidence intervals and hypothesis testing. These are vital to ensure that conclusions about the population are drawn accurately from the sample data.

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Most popular questions from this chapter

a. Use a computer (or random number table) to generate a random sample of 25 observations drawn from the following discrete probability distribution. $$\begin{array}{l|ccccc}\hline \boldsymbol{x} & 1 & 2 & 3 & 4 & 5 \\\\\boldsymbol{P}(\boldsymbol{x}) & 0.2 & 0.3 & 0.3 & 0.1 & 0.1 \\\\\hline\end{array}$$ Compare the resulting data to your expectations. b. Form a relative frequency distribution of the random data. c. Construct a probability histogram of the given distribution and a relative frequency histogram of the observed data using class midpoints of \(1,2,3,4,\) and 5. d. Compare the observed data with the theoretical distribution. Describe your conclusions. e. Repeat parts a through d several times with \(n=25 .\) Describe the variability you observe between samples. f. Repeat parts a through d several times with \(n=250 .\) Describe the variability you see between samples of this much larger size.

Let \(x\) be a random variable with the following probability distribution: $$\begin{array}{l|cccc}\hline x & 0 & 1 & 2 & 3 \\\P(x) & 0.4 & 0.3 & 0.2 & 0.1 \\\\\hline \end{array}$$ Does \(x\) have a binomial distribution? Justify your answer.

Where does all that Halloween candy go? The October 2004 issue of Readers' Digest quoted that "90\% of parents admit taking Halloween candy from their children's trick-or-treat bags." The source of information was the National Confectioners Association. Suppose that 25 parents are interviewed. What is the probability that 20 or more took Halloween candy from their children's trick-or-treat bags?

The employees at a General Motors assembly plant are polled as they leave work. Each is asked, "What brand of automobile are you riding home in?" The random variable to be reported is the number of each brand mentioned. Is \(x\) a binomial random variable? Justify your answer.

Can playing video games as a child and teenager lead to a gambling or substance addiction? According to the April \(11,2009, U S A\) Today article "Kids show addiction symptoms," research published in the Journal Psychological Science found that \(8.5 \%\) of video-gameplaying children and teens displayed behavioral signs that may indicate addiction. Suppose a randomly selected group of 30 video-gaming eighth-grade students is selected. a. What is the probability that exactly 2 will display addiction symptoms? b. If the study also indicated that \(12 \%\) of videogaming boys display addiction symptoms, what is the probability that exactly 2 out of the 17 boys in the group will display addiction symptoms? c. If the study also indicated that \(3 \%\) of video-gaming girls display addiction symptoms, what is the probability that exactly 2 out of the 13 girls in the group will display addiction symptoms?

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