The sample average is a random variable and

The sample average is a random variable and

A) is a single number and as a result cannot have a distribution.
B) has a probability distribution called its sampling distribution.
C) has a probability distribution called the standard normal distribution.
D) has a probability distribution that is the same as for the Y_1,... Y_n i.i.d. variables.

Answer: B

If variables with a multivariate normal distribution have covariances that equal zero, then

If variables with a multivariate normal distribution have covariances that equal zero, then

A) the correlation will most often be zero, but does not have to be.
B) the variables are independent.
C) you should use the distribution to calculate probabilities.
D) the marginal distribution of each of the variables is no longer normal.

Answer: B

Assume that Y is normally distributed N(miu, sigma) . Moving from the mean (miu) 1.96 standard deviations to the left and 1.96 standard deviations to the right, then the area under the normal p.d.f. is

Assume that Y is normally distributed N(miu, sigma) . Moving from the mean (miu) 1.96 standard
deviations to the left and 1.96 standard deviations to the right, then the area under the normal p.d.f.
is

A) 0.67
B) 0.05
C) 0.95
D) 0.33


Answer: C

To standardize a variable you

To standardize a variable you

A) subtract its mean and divide by its standard deviation.
B) integrate the area below two points under the normal distribution.
C) add and subtract 1.96 times the standard deviation to the variable.
D) divide it by its standard deviation, as long as its mean is 1.

Answer: A

The correlation between X and Y

The correlation between X and Y

A) cannot be negative since variances are always positive.
B) is the covariance squared.
C) can be calculated by dividing the covariance between X and Y by the product of the two
standard deviations.
D) is given by corr(X,Y) = COV(X,Y)/[VAR(X)*Var(Y)]

Answer: C

For a normal distribution, the skewness and kurtosis measures are as follows:

For a normal distribution, the skewness and kurtosis measures are as follows:

A) 1.96 and 4
B) 0 and 0
C) 0 and 3
D) 1 and 2

Answer: C