/*! 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 74 Suppose that instead of three sh... [FREE SOLUTION] | 91Ó°ÊÓ

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Suppose that instead of three shirts, each participant was asked to choose among four shirts and that the process was performed five times. If a person can't identify her roommate by smell and is just picking a shirt at random, then \(x=\) number of correct identifications is a binomial random variable with \(n=5\) and \(p=\frac{1}{4}\). a. What are the possible values of \(x\) ? b. For each possible value of \(x\), find the associated probability \(p(x)\) and display the possible \(x\) values and \(p(x)\) values in a table. (Hint: See Example 6.27.) c. Construct a histogram displaying the probability distribution of \(x\).

Short Answer

Expert verified
a. The possible values of \(x\) are \(\{0, 1, 2, 3, 4, 5\}\). b. The table of possible \(x\) values and associated probabilities \(p(x)\) is as follows: | x | p(x) | |---|---------| | 0 | 0.2373 | | 1 | 0.3955 | | 2 | 0.2637 | | 3 | 0.0889 | | 4 | 0.0146 | | 5 | 0.0010 | c. The histogram of the probability distribution has the following appearance: ``` 1.0 ┼ │ * 0.9 ┼ │ 0.8 ┼ │ 0.7 ┼ │ * 0.6 ┼ │ 0.5 ┼ │ * 0.4 ┼ │ 0.3 ┼ * │ 0.2 ┼ │ * 0.1 ┼ │ * 0.0 ┼ ├───┼───┼───┼───┼───┼───┼───┼───┼ 0 1 2 3 4 5 x ```

Step by step solution

01

a. Possible values of x

The number of correct identifications can range from 0 (no correct identifications) to 5 (all correct identifications). So, the possible values of \(x\) are \(\{0, 1, 2, 3, 4, 5\}\).
02

b. Calculating p(x) for each possible value of x

To calculate the probability \(p(x)\) of getting \(x\) correct identifications, we can use the Binomial Probability formula: \[p(x) = \binom{n}{x} p^x (1-p)^{n-x}\] In our case, \(n = 5\) and \(p = \frac{1}{4}\). So, for each possible value of \(x\), we can calculate \(p(x)\) as follows: 1. \(x = 0\): \(p(0) = \binom{5}{0} \left(\frac{1}{4}\right)^0 \left(1 - \frac{1}{4}\right)^{5-0} = 243 \cdot \frac{3^5}{4^5} \approx 0.2373\) 2. \(x = 1\): \(p(1) = \binom{5}{1} \left(\frac{1}{4}\right)^1 \left(1 - \frac{1}{4}\right)^{5-1} = 405 \cdot \frac{3^4}{4^5} \approx 0.3955\) 3. \(x = 2\): \(p(2) = \binom{5}{2} \left(\frac{1}{4}\right)^2 \left(1 - \frac{1}{4}\right)^{5-2} = 270 \cdot \frac{3^3}{4^5} \approx 0.2637\) 4. \(x = 3\): \(p(3) = \binom{5}{3} \left(\frac{1}{4}\right)^3 \left(1 - \frac{1}{4}\right)^{5-3} = 80 \cdot \frac{3^2}{4^5} \approx 0.0889\) 5. \(x = 4\): \(p(4) = \binom{5}{4} \left(\frac{1}{4}\right)^4 \left(1 - \frac{1}{4}\right)^{5-4} = 15 \cdot \frac{3^1}{4^5} \approx 0.0146\) 6. \(x = 5\): \(p(5) = \binom{5}{5} \left(\frac{1}{4}\right)^5 \left(1 - \frac{1}{4}\right)^{5-5}= 1 \cdot \frac{1}{4^5} \approx 0.0010\) Now, let's display the possible \(x\) values and the corresponding \(p(x)\) values in a table: | x | p(x) | |---|---------| | 0 | 0.2373 | | 1 | 0.3955 | | 2 | 0.2637 | | 3 | 0.0889 | | 4 | 0.0146 | | 5 | 0.0010 |
03

c. Histogram of the probability distribution

To construct a histogram displaying the probability distribution of \(x\), we can plot the \(x\) values on the horizontal axis and the corresponding \(p(x)\) values on the vertical axis. Each bar in the histogram represents an \(x\) value, and its height is equal to the value of \(p(x)\). The histogram will look like the following: ``` 1.0 ┼ │ * 0.9 ┼ │ 0.8 ┼ │ 0.7 ┼ │ * 0.6 ┼ │ 0.5 ┼ │ * 0.4 ┼ │ 0.3 ┼ * │ 0.2 ┼ │ * 0.1 ┼ │ * 0.0 ┼ ├───┼───┼───┼───┼───┼───┼───┼───┼ 0 1 2 3 4 5 x ``` In this histogram, we can see that the probability of getting 1 correct identification (\(x=1\)) is the highest, while the probabilities of getting all the identifications correct (\(x=5\)) or getting none of them correct (\(x=0\)) are the lowest.

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Key Concepts

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

Probability Distribution
Probability distribution describes how the values of a random variable are distributed. In simpler terms, it tells us what values the random variable can take and how likely it is for the variable to take on each of those values.
In the context of our problem, the variable of interest is the number of correct identifications a person makes while guessing. This variable, labeled as \(x\), is a binomial random variable with parameters \(n\) and \(p\). Here, \(n = 5\) represents the number of trials, and \(p = \frac{1}{4}\) represents the probability of a correct identification during any single trial.

The range of possible values for \(x\) is what forms our probability distribution. So, \(x\) can take values from 0 to 5, as these are the numbers of successful trials, or correct identifications, out of the five attempts. The essence of probability distribution is to attach a probability to each of these outcomes, essentially providing a complete picture of all possible occurrences.
Binomial Probability Formula
The Binomial Probability Formula is a mathematical formula used to calculate the probability of achieving a specific number of successful outcomes, in a fixed number of trials, where each trial has the same probability of success.
The formula is:\[p(x) = \binom{n}{x} p^x (1-p)^{n-x}\]where:
  • \(n\) is the total number of trials.
  • \(x\) is the number of successful outcomes you want to find the probability for.
  • \(p\) is the probability of success on any individual trial.
  • \(\binom{n}{x}\) is the binomial coefficient, representing the number of ways \(x\) successes can occur in \(n\) trials.

In our exercise, to find the probabilities of the outcomes for \(x = 0, 1, 2, 3, 4, 5\), we plugged each into this formula using \(n = 5\) and \(p = \frac{1}{4}\). This showed us how probable each of these outcomes was – ranging from no correct identifications (\(x = 0\)) to identifying correctly every time (\(x = 5\)).
Histogram Construction
A histogram is a graphical representation of the distribution of data. Constructing a histogram for a binomial distribution involves plotting each outcome of the random variable \(x\) against its probability \(p(x)\).
To build a histogram for the probability distribution from our solution, follow these steps:
  • Label the horizontal axis with the possible values for \(x\), in this case, 0 through 5.
  • Label the vertical axis with the probabilities \(p(x)\), ensuring the scale captures the highest probability in your distribution set.
  • For each value of \(x\), draw a bar where the height of the bar represents \(p(x)\).

The completed histogram provides a visual summary of the data, showing where the probabilities are concentrated among the possible outcomes. From our example, it's clear that getting 1 or 2 correct identifications is more probable, while getting all correct (or none) is fairly unlikely. This visual tool helps students quickly appreciate the distribution's characteristics.

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Most popular questions from this chapter

The paper referenced in Example 6.24 ("Estimating Waste Transfer Station Delays Using GPS," Waste Management [2008]: 1742-1750) describing processing times for garbage trucks also provided information on processing times at a second facility. At this second facility, the mean total processing time was 9.9 minutes and the standard deviation of the processing times was 6.2 minutes. Explain why a normal distribution with mean 9.9 and standard deviation 6.2 would not be an appropriate model for the probability distribution of the variable \(x=\) total processing time of a randomly selected truck entering this second facility.

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A soft-drink machine dispenses only regular Coke and Diet Coke. Sixty percent of all purchases from this machine are diet drinks. The machine currently has 10 cans of each type. If 15 customers want to purchase drinks before the machine is restocked, what is the probability that each of the 15 is able to purchase the type of drink desired?

Consider the random variable \(y=\) the number of broken eggs in a randomly selected carton of one dozen eggs. Suppose the probability distribution of \(y\) is as follows: \(\begin{array}{cccccc}y & 0 & 1 & 2 & 3 & 4 \\ p(y) & 0.65 & 0.20 & 0.10 & 0.04 & ?\end{array}\) a. Only \(y\) values of \(0,1,2,3,\) and 4 have probabilities greater than \(0 .\) What is \(p(4) ?\) b. How would you interpret \(p(1)=0.20 ?\) c. Calculate \(P(y \leq 2)\), the probability that the carton contains at most two broken eggs, and interpret this probability. d. Calculate \(P(y<2),\) the probability that the carton contains fewer than two broken eggs. Why is this smaller than the probability in Part (c)? e. What is the probability that the carton contains exactly 10 unbroken eggs? f. What is the probability that at least 10 eggs are unbroken?

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