Mathematical Methods in the Physical Sciences
3rd Edition
ISBN: 9780471198260
Author: Mary L. Boas
Publisher: Wiley, John & Sons, Incorporated
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Chapter 15.6, Problem 16P
To determine
The proof that
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Suppose X, Y joint Gaussian with s.d.'s 2 and 3 respectively and
covariance 4. Find the joint pdf and the two marginal pdf's. What if
the covariance were 8?
Y
= X,
Problem 6: Let X~ U(0, 1), and suppose Y|X =X~ N(x,x²). Find the joint distribution of U
V = X and show they are independent.
=
Suppose that Y₁ and Y₂ are uniformly distributed over the triangle shaded in the accompanying figure.
3₂
(0, 1)
(-1,0)
(a) Find Cov(Y₁ Y₂).
Cov(Y₁, Y₂)
=
(b) Are Y₁ and Y₂ independent?
Yes
O No
(1, 0)
(c) Find the coefficient of correlation for Y₁ and Y₂.
P=
y/₁
(d) Does your answer to part (b) lead you to doubt your answer to part (a)? Why or why not?
O Even though Cov(Y₁Y₂) # 0, Y₁ and Y₂ are not necessarily dependent.
Since Cov(Y₁ Y₂) # 0, we should expect Y₁ and Y₂ to be dependent.
O Since Cov(Y₁, Y₂) = 0, we should expect Y₁ and Y₂ to be independent.
O Even though Cov(Y₁Y₂) = 0, Y₁ and Y₂ are not necessarily independent.
Chapter 15 Solutions
Mathematical Methods in the Physical Sciences
Ch. 15.1 - If you select a three-digit number at random, what...Ch. 15.1 - Three coins are tossed; what is the probability...Ch. 15.1 - In a box there are 2 white, 3 black, and 4 red...Ch. 15.1 - A single card is drawn at random from a shuffled...Ch. 15.1 - Given a family of two children (assume boys and...Ch. 15.1 - A trick deck of cards is printed with the hearts...Ch. 15.1 - A letter is selected at random from the alphabet....Ch. 15.1 - An integer N is chosen at random with 1N100. What...Ch. 15.1 - You are trying to find instrument A in a...Ch. 15.1 - A shopping mall has four entrances, one on the...
Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up an appropriate sample space for each of...Ch. 15.2 - Set up several nonuniform sample spaces for the...Ch. 15.2 - Use the sample space of Example 1 above, or one or...Ch. 15.2 - A student claims in Problem 1.5 that if one child...Ch. 15.2 - Two dice are thrown. Use the sample space ( 2.4 )...Ch. 15.2 - Use both the sample space (2.4) and the sample...Ch. 15.2 - Given an nonuniform sample space and the...Ch. 15.2 - Two dice are thrown. Given the information that...Ch. 15.2 - Are the following correct nomuniform sample spaces...Ch. 15.2 - Consider the set of all permutations of the...Ch. 15.3 - (a) Set up a sample space for the 5 black and 10...Ch. 15.3 - Prove (3.1) for a nonuniform sample space. Hints:...Ch. 15.3 - What is the probability of getting the sequence...Ch. 15.3 - (a) A weighted coin has probability of 23 of...Ch. 15.3 - What is the probability that a number n,1n99, is...Ch. 15.3 - A card is selected from a shuffled deck. What is...Ch. 15.3 - (a) Note that (3.4) assumes P(A)0 since PA(B) is...Ch. 15.3 - Show that...Ch. 15.3 - Prob. 9PCh. 15.3 - Three typed letters and their envelopes are piled...Ch. 15.3 - In paying a bill by mail, you want to put your...Ch. 15.3 - (a) A loaded die has probabilities...Ch. 15.3 - (a) A candy vending machine is out of order. The...Ch. 15.3 - A basketball player succeeds in making a basket 3...Ch. 15.3 - Use Bayes' formula ( 3.8 ) to repeat these simple...Ch. 15.3 - Suppose you have 3 nickels and 4 dimes in your...Ch. 15.3 - (a) There are 3 red and 5 black balls in one box...Ch. 15.3 - Two cards are drawn at random from a shuffled...Ch. 15.3 - Suppose it is known that 1 of the population have...Ch. 15.3 - Some transistors of two different kinds (call them...Ch. 15.3 - Two people are taking turns tossing a pair of...Ch. 15.3 - Repeat Problem 21 if the players toss a pair of...Ch. 15.3 - A thick coin has 37 probability of falling heads,...Ch. 15.4 - (a) There are 10 chairs in a row and 8 people to...Ch. 15.4 - In the expansion of (a+b)n (see Example 2), let...Ch. 15.4 - A bank allows one person to have only one savings...Ch. 15.4 - Five cards are dealt from a shuffled deck. What is...Ch. 15.4 - A bit (meaning binary digit) is 0 or 1. An ordered...Ch. 15.4 - A so-called 7 -way lamp has three 60 -watt bulbs...Ch. 15.4 - What is the probability that the 2 and 3 of clubs...Ch. 15.4 - Two cards are drawn from a shuffled deck. What is...Ch. 15.4 - Two cards are drawn from a shuffled deck. What is...Ch. 15.4 - What is the probability that you and a friend have...Ch. 15.4 - The following game was being played on a busy...Ch. 15.4 - Consider Problem 10 for different months of birth....Ch. 15.4 - Generalize Example 3 to show that the number of...Ch. 15.4 - (a) Find the probability that in two tosses of a...Ch. 15.4 - Set up the uniform sample spaces for the problem...Ch. 15.4 - Do Problem 15 for 2 particles in 2 boxes. Using...Ch. 15.4 - Find the number of ways of putting 2 particles in...Ch. 15.4 - Find the number of ways of putting 3 particles in...Ch. 15.4 - (a) Following the methods of Examples 3, 4, and 5,...Ch. 15.4 - (a) In Example 5, a mathematical model is...Ch. 15.4 - The following problem arises in quantum mechanics...Ch. 15.4 - Suppose 13 people want to schedule a regular...Ch. 15.4 - Do Problem 22 if one person is busy 3 evenings,...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Set up sample spaces for Problems 1 to 7 and list...Ch. 15.5 - Would you pay $10 per throw of two dice if you...Ch. 15.5 - Prob. 9PCh. 15.5 - Let be the average of the random variable x. Then...Ch. 15.5 - Show that the expected number of heads in a single...Ch. 15.5 - Use Problem 9 to find the expected value of the...Ch. 15.5 - Show that adding a constant K to a random variable...Ch. 15.5 - As in Problem 11, show that the expected number of...Ch. 15.5 - Use Problem 9 to find x in Problem 7.Ch. 15.5 - Show that 2=Ex22. Hint: Write the definition of 2...Ch. 15.5 - Use Problem 16 to find in Problems 2, 6, and 7.Ch. 15.6 - (a) Find the probability density function f(x) for...Ch. 15.6 - It is shown in the kinetic theory of gases that...Ch. 15.6 - A ball is thrown straight up and falls straight...Ch. 15.6 - In Problem 1 we found the probability density...Ch. 15.6 - The probability for a radioactive particle to...Ch. 15.6 - A circular garden bed of radius 1m is to be...Ch. 15.6 - (a) Repeat Problem 6 where the circular area is...Ch. 15.6 - Given that a particle is inside a sphere of radius...Ch. 15.6 - Prob. 9PCh. 15.6 - Do Problem 5.10 for a continuous distribution.Ch. 15.6 - Do Problem 5.13 for a continuous distribution.Ch. 15.6 - Do Problem 5.16 for a continuous distribution.Ch. 15.6 - Prob. 13PCh. 15.6 - Prob. 14PCh. 15.6 - Show that the covariance of two independent (see...Ch. 15.6 - Prob. 16PCh. 15.7 - For the values of n indicated in Problems 1 to 4 :...Ch. 15.7 - For the values of n indicated in Problems 1 to 4:...Ch. 15.7 - For the values of n indicated in Problems 1 to 4:...Ch. 15.7 - For the values of n indicated in Problems 1 to 4:...Ch. 15.7 - Write the formula for the binomial density...Ch. 15.7 - For the given values of n and p in Problems 6 to...Ch. 15.7 - For the given values of n and p in Problems 6 to...Ch. 15.7 - For the given values of n and p in problems 6 to...Ch. 15.7 - Use the second method of Problem 5.11 to show that...Ch. 15.7 - Show that the most probable number of heads in n...Ch. 15.7 - Use the method of Problem 10 to show that for the...Ch. 15.7 - Let x= number of heads in one toss of a coin. What...Ch. 15.7 - Generalize Problem 12 to show that for the general...Ch. 15.8 - Verify that for a random variable x with normal...Ch. 15.8 - Do Problem 6.4 by comparing eax2 with f(x) in...Ch. 15.8 - The probability density function for the x...Ch. 15.8 - Prob. 4PCh. 15.8 - Computer plot on the same axes the normal density...Ch. 15.8 - Do Problem 5 for =16,13,1.Ch. 15.8 - By computer find the value of the normal...Ch. 15.8 - Carry through the following details of a...Ch. 15.8 - Computer plot a graph like Figure 8.3 of the...Ch. 15.8 - Computer plot graphs like Figure 8.2 but with p12...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.8 - As in Examples 1 and 2, use (a) the binomial...Ch. 15.9 - Solve the sequence of differential equations (9.4)...Ch. 15.9 - Show that the average value of a random variable n...Ch. 15.9 - In an alpha-particle counting experiment the...Ch. 15.9 - Suppose you receive an average of 4 phone calls...Ch. 15.9 - Suppose that you have 5 exams during the 5 days of...Ch. 15.9 - If you receive, on the average, 5 email messages...Ch. 15.9 - In a club with 500 members, what is the...Ch. 15.9 - If there are 100 misprints in a magazine of 40...Ch. 15.9 - If there are, on the average, 7 defects in a new...Ch. 15.9 - Derive equation ( 9.9 ) as follows: In C(n,x),...Ch. 15.9 - Suppose 520 people each have a shuffled deck of...Ch. 15.9 - Computer plot on the same axes graphs of the...Ch. 15.9 - Computer plot on the same axes a graph of the...Ch. 15.10 - Let m1,m2,,mn be a set of measurements, and define...Ch. 15.10 - Let x1,x2,,xn be independent random variables,...Ch. 15.10 - Define s by the equation s2=(1/n)i=1nxix2. Show...Ch. 15.10 - Assuming a normal distribution, find the limits h...Ch. 15.10 - Show that if w=xy or w=x/y, then ( 10.14) gives...Ch. 15.10 - By expanding w(x,y,z) in a three-variable power...Ch. 15.10 - Prob. 7PCh. 15.10 - The following measurements of x and y have been...Ch. 15.10 - Given the measurements...Ch. 15.10 - Given the measurements...Ch. 15.11 - (a) Suppose you have two quarters and a dime in...Ch. 15.11 - (a) Suppose that Martian dice are regular...Ch. 15.11 - There are 3 red and 2 white balls in one box and 4...Ch. 15.11 - If 4 letters are put at random into 4 envelopes,...Ch. 15.11 - Two decks of cards are matched, that is, the order...Ch. 15.11 - Find the number of ways of putting 2 particles in...Ch. 15.11 - Suppose a coin is tossed three times. Let x be a...Ch. 15.11 - (a) A weighted coin has probability 23 of coming...Ch. 15.11 - One box contains one die and another box contains...Ch. 15.11 - Do Problems 10 to 12 using both the binomial...Ch. 15.11 - Do Problems 10 to 12 using both the binomial...Ch. 15.11 - Do Problems 10 to 12 using both the binomial...Ch. 15.11 - A radioactive source emits 1800 particles during...Ch. 15.11 - Suppose a 200-page book has, on the average, one...Ch. 15.11 - In Problems 15 and 16, find the binomial...Ch. 15.11 - In Problems 15 and 16, find the binomial...Ch. 15.11 - Given the measurements...Ch. 15.11 - Given the measurements...
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