1. Suppose that Z1,Z2 are independent standard normal random
variables. Let Y1 = Z1 − 2Z2, Y2 = Z1 − Z2.
(a) Find the joint pdf fY1,Y2(y1,y2). Don’t use the change of
variables theorem – all of that work has already been done for you.
Instead, evaluate the matrices Σ and Σ−1, then multiply the
necessary matrices and vectors to obtain a formula for
fY1,Y2(y1,y2) containing no matrices and no vectors.
(b) Find the marginal pdf fY2 (y2). Don’t use...
Provide an example that if the
cov(X,Y)
= 0, the two random variables, X and Y, are not necessarily
independent.
Would you please give the example specifically and
why?
Provide an example that if the
cov(X,Y)
= 0, the two random variables, X and Y, are not necessarily
independent.
Would you please give the example specifically and
why?
A: Suppose two random variables X and Y are independent and
identically distributed as standard normal. Specify the joint
probability density function f(x, y) of X and Y.
Next, suppose two random variables X and Y are independent and
identically distributed as Bernoulli with parameter 1 2 . Specify
the joint probability mass function f(x, y) of X and Y.
B: Consider a time series realization X = [10, 15, 23, 20, 19]
with a length of five-periods. Compute the...
Suppose that X1 and X2 are two random variables. Suppose that X1
has mean 1 and variance 4 while X2 has mean 3 and variance 9.
Finally, suppose that the correlation between X1 and X2 is 3/8.
Denote Y = 2X1 − X2. (67) The mean of Y is (a) 1 (b) 4 (c) -2 (d)
-1 (68) The variance of Y is (a) 25 (b) 4 (c) 9 (d) 16 (69) The
standard deviation of Y is (a) 5...
Let X and Y be random variables. Suppose P(X = 0, Y = 0) = .1,
P(X = 1, Y = 0) = .3, P(X = 2, Y = 0) = .2 P(X = 0, Y = 1) = .2,
P(X = 1, Y = 1) = .2, P(X = 2, Y = 1) = 0.
a. Determine E(X) and E(Y ).
b. Find Cov(X, Y )
c. Find Cov(2X + 3Y, Y ).
Suppose Z denotes the standard normal random variable. Compute
the following
a) P (Z > 2)
b) P(-1 < Z < 2.31)
c) P (1.21 < Z < 2.42)
d) P (Z < 1.37)
e) P (Z > -1)
Show working
Suppose that X and Y are two normally distributed random
variables. X has mean 2 and standard deviation 3.Y has mean 3 and
standard deviation 2. Their correlation is 0.6
. What is the mean and standard deviation of X + Y ?What is the
distribution of X + Y ? What if X and Y are jointly normally
distributed? What if they are not jointly normally distributed?
Explain your answer.
Suppose that X and Y are two normally distributed random
variables. X has mean 2 and standard deviation 3.Y has mean 3 and
standard deviation 2. Their correlation is 0.6
. What is the mean and standard deviation of X + Y? What is the
distribution of X + Y? What if X and Y are jointly normally
distributed? What if they are not jointly normally distributed?
Explain your answer. (Why we cannot conclude if they are not
jointly normally...
On the overlap of two events, suppose two events A and B ,
P(A)=1/2, P(B)=2/3, but we have no more information about the
event, what are the maximum and minimum possible values of
P(A/B)