Mathematical Statistics with Applications
7th Edition
ISBN: 9780495110811
Author: Dennis Wackerly, William Mendenhall, Richard L. Scheaffer
Publisher: Cengage Learning
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Question
Chapter 5.3, Problem 29E
a.
To determine
Find the marginal density
b.
To determine
Find the value of
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For a certain psychiatric clinic suppose that the random variable X represents the total time (in minutes) that a typical patient spends in this clinic during a typical visit (where this total time is the sum of the waiting time and the treatment time), and that the random variable Y represents the waiting time (in minutes) that a typical patient spends in the waiting room before starting treatment with a psychiatrist. Further, suppose that X and Y can be assumed to follow the bivariate density function
fXY(x,y)=λ2e−λx, 0<y<x, where λ > 0 is a known parameter value.
(a) Find the marginal density fX(x) for the total amount of time spent at the clinic.
(b) Find the conditional density for waiting time, given the total time.
(c) Find P (Y > 20 | X = x), the probability a patient waits more than 20 minutes if their total clinic visit is x minutes.
(Hint: you will need to consider two cases, if x < 20 and if x ≥ 20.)
Suppose that X has the density function c(x) = CX2 for 0 ≤ x ≤ 1 and f(x) = 0 otherwise.a. Find c.b. Find the cdf.c. What is P(.1≤ X <.5)?
Let X denote 0.025 × the ambient air temperature (˚C) and let Y denote the time (min) that it takes for a diesel engine to warm up. Assume that (X, Y) has joint probability density function
f(x,y) = cx (1 − x)(6 + 5x − 4y), for 0 < x < 1, 0 < y < 0.5.
Find the conditional pdf of Y, given X = x. Compare this to the marginal pdf of Y. Are air temperature and engine warm-up time independent?
Chapter 5 Solutions
Mathematical Statistics with Applications
Ch. 5.2 - Contracts for two construction jobs are randomly...Ch. 5.2 - Three balanced coins are tossed independently. One...Ch. 5.2 - Of nine executives in a business firm, four are...Ch. 5.2 - Given here is the joint probability function...Ch. 5.2 - Refer to Example 5.4. The joint density of Y1, the...Ch. 5.2 - Prob. 6ECh. 5.2 - Let Y1 and Y2 have joint density function...Ch. 5.2 - Prob. 8ECh. 5.2 - Prob. 9ECh. 5.2 - An environmental engineer measures the amount (by...
Ch. 5.2 - Suppose that Y1 and Y2 are uniformly distributed...Ch. 5.2 - Prob. 12ECh. 5.2 - Prob. 13ECh. 5.2 - Prob. 14ECh. 5.2 - The management at a fast-food outlet is interested...Ch. 5.2 - Let Y1 and Y2 denote the proportions of time (out...Ch. 5.2 - Let (Y1, Y2) denote the coordinates of a point...Ch. 5.2 - Prob. 18ECh. 5.3 - In Exercise 5.1, we determined that the joint...Ch. 5.3 - Refer to Exercise 5.2. a Derive the marginal...Ch. 5.3 - In Exercise 5.3, we determined that the joint...Ch. 5.3 - In Exercise 5.4, you were given the following...Ch. 5.3 - In Example 5.4 and Exercise 5.5, we considered the...Ch. 5.3 - Prob. 24ECh. 5.3 - Prob. 25ECh. 5.3 - Prob. 26ECh. 5.3 - Prob. 27ECh. 5.3 - In Exercise 5.10, we proved that...Ch. 5.3 - Prob. 29ECh. 5.3 - In Exercise 5.12, we were given the following...Ch. 5.3 - In Exercise 5.13, the joint density function of Y1...Ch. 5.3 - Prob. 32ECh. 5.3 - Suppose that Y1 is the total time between a...Ch. 5.3 - Prob. 34ECh. 5.3 - Prob. 35ECh. 5.3 - Prob. 36ECh. 5.3 - Prob. 37ECh. 5.3 - Let Y1 denote the weight (in tons) of a bulk item...Ch. 5.3 - Prob. 39ECh. 5.3 - Prob. 40ECh. 5.3 - Prob. 41ECh. 5.3 - Prob. 42ECh. 5.4 - Let Y1 and Y2 have joint density function f(y1,...Ch. 5.4 - Prob. 44ECh. 5.4 - Prob. 45ECh. 5.4 - Prob. 46ECh. 5.4 - In Exercise 5.3, we determined that the joint...Ch. 5.4 - In Exercise 5.4, you were given the following...Ch. 5.4 - In Example 5.4 and Exercise 5.5, we considered the...Ch. 5.4 - Prob. 50ECh. 5.4 - Prob. 51ECh. 5.4 - Prob. 52ECh. 5.4 - Prob. 53ECh. 5.4 - Prob. 54ECh. 5.4 - Prob. 55ECh. 5.4 - In Exercise 5.12, we were given the following...Ch. 5.4 - Prob. 57ECh. 5.4 - Suppose that the random variables Y1 and Y2 have...Ch. 5.4 - If Y1 is the total time between a customers...Ch. 5.4 - Prob. 60ECh. 5.4 - Prob. 61ECh. 5.4 - Prob. 62ECh. 5.4 - Let Y1 and Y2 be independent exponentially...Ch. 5.4 - Prob. 64ECh. 5.4 - Prob. 65ECh. 5.4 - Let F1(y1) and F2(y2) be two distribution...Ch. 5.4 - Prob. 67ECh. 5.4 - Prob. 68ECh. 5.4 - The length of life Y for fuses of a certain type...Ch. 5.4 - A bus arrives at a bus stop at a uniformly...Ch. 5.4 - Prob. 71ECh. 5.6 - In Exercise 5.1, we determined that the joint...Ch. 5.6 - Prob. 73ECh. 5.6 - Refer to Exercises 5.6, 5.24, and 5.50. Suppose...Ch. 5.6 - Prob. 75ECh. 5.6 - Prob. 76ECh. 5.6 - Prob. 77ECh. 5.6 - Prob. 78ECh. 5.6 - Suppose that, as in Exercise 5.11, Y1 and Y2 are...Ch. 5.6 - In Exercise 5.16, Y1 and Y2 denoted the...Ch. 5.6 - In Exercise 5.18, Y1 and Y2 denoted the lengths of...Ch. 5.6 - In Exercise 5.38, we determined that the joint...Ch. 5.6 - Prob. 83ECh. 5.6 - In Exercise 5.62, we considered two individuals...Ch. 5.6 - Prob. 85ECh. 5.6 - Prob. 86ECh. 5.6 - Prob. 87ECh. 5.6 - Prob. 88ECh. 5.7 - In Exercise 5.1, we determined that the joint...Ch. 5.7 - Prob. 90ECh. 5.7 - In Exercise 5.8, we derived the fact that...Ch. 5.7 - Prob. 92ECh. 5.7 - Suppose that, as in Exercises 5.11 and 5.79, Y1...Ch. 5.7 - Prob. 94ECh. 5.7 - Prob. 95ECh. 5.7 - Prob. 96ECh. 5.7 - The random variables Y1 and Y2 are such that E(Y1)...Ch. 5.7 - Prob. 98ECh. 5.7 - Prob. 99ECh. 5.7 - Let Z be a standard normal random variable and let...Ch. 5.7 - Prob. 101ECh. 5.8 - A firm purchases two types of industrial...Ch. 5.8 - Prob. 103ECh. 5.8 - Prob. 104ECh. 5.8 - Prob. 105ECh. 5.8 - In Exercise 5.9, we determined that...Ch. 5.8 - In Exercise 5.12, we were given the following...Ch. 5.8 - If Y1 is the total time between a customers...Ch. 5.8 - In Exercise 5.16, Y1 and Y2 denoted the...Ch. 5.8 - Suppose that Y1 and Y2 have correlation...Ch. 5.8 - Prob. 111ECh. 5.8 - In Exercise 5.18, Y1 and Y2 denoted the lengths of...Ch. 5.8 - A retail grocery merchant figures that her daily...Ch. 5.8 - For the daily output of an industrial operation,...Ch. 5.8 - Prob. 115ECh. 5.8 - Prob. 116ECh. 5.8 - A population of N alligators is to be sampled in...Ch. 5.8 - Prob. 118ECh. 5.9 - A learning experiment requires a rat to run a maze...Ch. 5.9 - Prob. 120ECh. 5.9 - Refer to Exercise 5.117. Suppose that the number N...Ch. 5.9 - The weights of a population of mice fed on a...Ch. 5.9 - Prob. 123ECh. 5.9 - The typical cost of damages caused by a fire in a...Ch. 5.9 - When commercial aircraft are inspected, wing...Ch. 5.9 - Prob. 126ECh. 5.9 - Prob. 127ECh. 5.10 - Let Y1 and Y2 have a bivariate normal...Ch. 5.10 - Prob. 129ECh. 5.10 - Prob. 130ECh. 5.10 - Prob. 131ECh. 5.10 - Prob. 132ECh. 5.11 - Prob. 133ECh. 5.11 - Prob. 134ECh. 5.11 - In Exercise 5.41, we considered a quality control...Ch. 5.11 - In Exercise 5.42, the number of defects per yard...Ch. 5.11 - In Exercise 5.38, we assumed that Y1, the weight...Ch. 5.11 - Assume that Y denotes the number of bacteria per...Ch. 5.11 - Prob. 139ECh. 5.11 - Prob. 140ECh. 5.11 - Let Y1 have an exponential distribution with mean ...Ch. 5.11 - Prob. 142ECh. 5.11 - Prob. 143ECh. 5 - Prove Theorem 5.9 when Y1 and Y2 are independent...Ch. 5 - Prob. 145SECh. 5 - Prob. 146SECh. 5 - Two friends are to meet at the library. Each...Ch. 5 - Prob. 148SECh. 5 - Prob. 149SECh. 5 - Prob. 150SECh. 5 - The lengths of life Y for a type of fuse has an...Ch. 5 - In the production of a certain type of copper, two...Ch. 5 - Suppose that the number of eggs laid by a certain...Ch. 5 - In a clinical study of a new drug formulated to...Ch. 5 - Prob. 155SECh. 5 - Refer to Exercise 5.86. Suppose that Z is a...Ch. 5 - Prob. 157SECh. 5 - Prob. 158SECh. 5 - Prob. 159SECh. 5 - Prob. 160SECh. 5 - Suppose that we are to observe two independent...Ch. 5 - Prob. 162SECh. 5 - Prob. 163SECh. 5 - Prob. 164SECh. 5 - Prob. 165SECh. 5 - Prob. 166SECh. 5 - Prob. 167SE
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- Suppose that X and Y have a joint probability density function f(x,y)= 1, if0<y<1,y<x<2y; 0, otherwise. (a) Compute P(X + Y less than or equal 1). (b) Find the marginal probability density functions for X and Y , respectively. (c) Are X and Y independent?arrow_forward(a∗ ) Compute P(X = 4, Y = 5). (b∗ ) Compute the marginal pmf’s of X and Y . (c∗ ) Are X and Y independent? Let Z be the minimum of X and Y . Calculate E[Z].arrow_forwarda. What is the joint marginal PDF of X and Z?b. What is [P 0 <= Y <= 3/2 | X = 1/3 Z = 5/2]?arrow_forward
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