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...
Suppose that a firm has the p production function
f(x1; x2) = sqrt(x1) + x2^2.
(a) The marginal product of factor 1 (increases,
decreases, stays constant) ------------ as the amount of factor 1
increases. The marginal product of factor 2 (increases, decreases,
stays constant) ----------- as the amount of factor 2
increases.
(b) This production function does not satisfy the
definition of increasing returns to scale, constant returns to
scale, or decreasing returns to scale. How can this be?
(c)Find...