Chapter 3: Problem 19
Let an unbiased die be cast at random seven independent times. Compute the conditional probability that each side appears at least once given that side 1 appears exactly twice.
/*! 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}
Learning Materials
Features
Discover
Chapter 3: Problem 19
Let an unbiased die be cast at random seven independent times. Compute the conditional probability that each side appears at least once given that side 1 appears exactly twice.
All the tools & learning materials you need for study success - in one app.
Get started for free
. Let \(X_{1}, X_{2}, \ldots, X_{n}\) denote \(n\) mutually independent random variables with the moment-generating functions \(M_{1}(t), M_{2}(t), \ldots, M_{n}(t)\), respectively. (a) Show that \(Y=k_{1} X_{1}+k_{2} X_{2}+\cdots+k_{n} X_{n}\), where \(k_{1}, k_{2}, \ldots, k_{n}\) are real constants, has the mgf \(M(t)=\prod_{1}^{n} M_{i}\left(k_{i} t\right)\).
Let \(X\) and \(Y\) be independent random variables, each with a distribution that is \(N(0,1) .\) Let \(Z=X+Y .\) Find the integral that represents the cdf \(G(z)=\) \(P(X+Y \leq z)\) of \(Z .\) Determine the pdf of \(Z\). Hint: We have that \(G(z)=\int_{-\infty}^{\infty} H(x, z) d x\), where $$ H(x, z)=\int_{-\infty}^{z-x} \frac{1}{2 \pi} \exp \left[-\left(x^{2}+y^{2}\right) / 2\right] d y $$ Find \(G^{\prime}(z)\) by evaluating \(\int_{-\infty}^{\infty}[\partial H(x, z) / \partial z] d x\).
Show that the moment generating function of the negative binomial distribution is \(M(t)=p^{r}\left[1-(1-p) e^{t}\right]^{-r}\). Find the mean and the variance of this distribution. Hint: In the summation representing \(M(t)\), make use of the MacLaurin's series for \((1-w)^{-r}\)
Compute \(P\left(X_{1}+2 X_{2}-2 X_{3}>7\right)\), if \(X_{1}, X_{2}, X_{3}\) are iid with common distribution \(N(1,4)\).
If \(M\left(t_{1}, t_{2}\right)\) is the mgf of a bivariate normal distribution, compute the covariance by using the formula $$ \frac{\partial^{2} M(0,0)}{\partial t_{1} \partial t_{2}}-\frac{\partial M(0,0)}{\partial t_{1}} \frac{\partial M(0,0)}{\partial t_{2}} $$ Now let \(\psi\left(t_{1}, t_{2}\right)=\log M\left(t_{1}, t_{2}\right) .\) Show that \(\partial^{2} \psi(0,0) / \partial t_{1} \partial t_{2}\) gives this covariance directly.
What do you think about this solution?
We value your feedback to improve our textbook solutions.