/*! 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 258 Two chips are drawn at random an... [FREE SOLUTION] | 91Ó°ÊÓ

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Two chips are drawn at random and without replacement from an urn that contains five chips, numbered 1 through 5 . If the sum of the chips drawn is even, the random variable \(X\) equals 5 ; if the sum of the chips drawn is odd, \(X=-3\). Find the moment-generating function for \(X\).

Short Answer

Expert verified
The moment-generating function for the random variable \(X\) given the conditions is \(M(t) = 0.6 \times e^{5t} + 0.4 \times e^{-3t}\)

Step by step solution

01

Identify all possible combinations

First, identify all possible combinations of chips that can be drawn. Since there are 5 chips, the total number of ways to draw 2 chips without replacement is given by \( \binom{5}{2} = 10 \). These combinations would be: (1,2), (1,3), (1,4), (1,5), (2,3), (2,4), (2,5), (3,4), (3,5) and (4,5).
02

Determine the probability of each possible sum

Each combination results in a number which could be either even or odd. Out of 10 combinations, 6 yield an even sum (2,4,6,6,8) and 4 yield an odd sum (3,5,7,9). This corresponds to \(X = 5\) for even sums and \(X = -3\) for odd sums. Therefore, the corresponding probabilities are \(P(X=5) = 6/10 = 0.6\) and \(P(X=-3) = 4/10 = 0.4 \).
03

Calculate the moment-generating function

The moment-generating function \(M(t)\) of a random variable \(X\) is defined as \(M(t) = E(e^{tX})\). Using properties of expected values and linearity of expectation, it can be calculated as \(M(t) = e^{5t} \times P(X=5) + e^{-3t} \times P(X=-3)\). With substitution, the function will lead to \(M(t) = 0.6 \times e^{5t} + 0.4 \times e^{-3t}\).

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Key Concepts

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

Probability Theory
Probability theory is a mathematical framework for quantifying the uncertainty of events and predicting the likelihood of various outcomes. It provides a way to model and analyze phenomena where the result is uncertain. In our exercise, probability theory underpins the process of determining the odds of drawing chip combinations from an urn.

The exercise uses combinatorial analysis to determine the possible sums of two drawn chips and assigns probabilities to each outcome—0.6 for even sums and 0.4 for odd sums. When evaluating the properties of a random variable, such as calculating the moment-generating function (MGF), probability theory is crucial. The MGF itself is an integral part of probability theory, providing insights into the characteristics of a random variable such as its expected value and variance.
Random Variable
A random variable is a numerical outcome of a random process. It assigns real numbers to each outcome of a probabilistic event. In our case, the random variable, denoted by \(X\), is defined by the sum of the numbers on the two drawn chips. Depending on whether the sum is even or odd, \(X\) takes the values of 5 or -3, respectively.

After determining the probabilities associated with each value of \(X\), we use these probabilities to compute the MGF. The MGF of a random variable is a function that encodes information about all moments of the random variable (such as means and variances) and is particularly useful because it uniquely characterizes the probability distribution of the variable. Therefore, understanding the nature of the random variable is crucial for applying the correct methods to find the MGF.
Combinatorics
Combinatorics is the branch of mathematics focused on counting, arranging, and finding patterns in sets of elements. In probability and statistics, combinatorial methods are used to count outcomes and determine their likelihood. In the given exercise, combinatorics is used to find the total number of ways two chips can be drawn from five, which is a fundamental combinatorial task.

This counting process is achieved using combinations, denoted by \(\binom{n}{k}\), which describes the number of ways to choose \(k\) elements from a set of \(n\) without regard to order. By solving \(\binom{5}{2}\), we determine there are ten possible ways to draw two chips, providing a foundational step in calculating probabilities needed for the MGF. Effective use of combinatorial principles is essential in many probabilistic scenarios, as it allows for the systematic calculation of event probabilities that feed into further statistical analysis such as the moment-generating function.

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