Let X, Y and Z be independent random variables, each uniformly
distributed on the interval (0,1).
(a) Find the cumulative distribution function of X/Y.
(b) Find the cumulative distribution function of XY.
(c) Find the mean and variance of XY/Z.
Let X and Y be independent and uniformly distributed random
variables on [0, 1]. Find the cumulative distribution and
probability density function of Z = X + Y.
Let X and Y be uniformly distributed independent random
variables on [0, 1].
a) Compute the expected value E(XY ).
b) What is the probability density function fZ(z) of Z = XY
?
Hint: First compute the cumulative distribution function FZ(z) =
P(Z ≤ z) using a double integral, and then differentiate in z.
c) Use your answer to b) to compute E(Z). Compare it with your
answer to a).
Let X and Y be independent continuous random variables, with
each one uniformly distributed in the interval from 0 to1. Compute
the probability of the following event.
XY<=1/7
Let Y and Z be independent continuous random variables, both
uniformly distributed between 0 and 1.
1. Find the CDF of |Y − Z|.
2. Find the PDF of |Y − Z|.
9.8 Let X and Y be independent random variables with probability
distributions given by
P(X = 0) = P(X = 1) = 1/2 and P(Y = 0) = P(Y = 2) = 1/2 .
a. Compute the distribution of Z = X + Y .
b. Let Y˜ and Z˜ be independent random variables, where Y˜ has
the same distribution as Y , and Z˜ the same distribution as Z.
Compute the distribution of X˜ = Z˜ − Y
Suppose that z = xy, where x and y are independent and normally distributed random variables. The mean and variance of x are µx = 10 and σ2x = 2. The mean and variance of y are µy = 15 and σ2y = 3. Find the mean and variance of z by simulation. Does µz = µxµy? Does σ2z = σ2x σ2y? Do this for 100, 1000, and 5000 trials.
The joint density function for random variables X,
Y, and Z is
f(x, y,
z)= Cxyz if 0 ≤
x ≤ 1, 0 ≤ y ≤ 2, 0 ≤
z ≤ 2, and
f(x, y,
z) = 0 otherwise.
(a) Find the value of the constant C.
(b) Find P(X ≤ 1, Y ≤ 1, Z ≤ 1).
(c) Find P(X + Y + Z ≤ 1).
Assume that X, Y, and Z are independent random variables and
that each of the random variables have a mean of 1. Further, assume
σX = 1, σY = 2, and σZ = 3. Find
the mean and standard deviation of the following random
variables:
a. U = X + Y + Z
b. R = (X + Y + Z)/3
c. T = 2·X + 5·Y
d. What is the correlation between X and Y?
e. What is the...
Let X and Z be two independently distributed standard normal
random variables and let Y=X2+Z.
iShow thatE(Y|X) =X2
iiShow thatμY= 1
iiiShow thatE(XY) = 0ivShow that cov(X,Y) = 0 and thus ρX,Y=
0