1.) Suppose X is a random variable with mean 10 and variance 16.

Suppose Y is a random variable with mean 20 and variance 9.

X and Y are independent.

What is the standard deviation of the difference X - Y?

Group of answer choices

A.) square root of 7

B.) 25

C.) None of the other choices is correct

D.) 7

E.) 5

2.) Suppose X is time to take a portion of the SAT test and f(x) = x/8 from 0 to 4 hours.

Find P(X =2) and f(2).

Group of answer choices

A.) 0, 2

B.) 0, 1/4

C.) 1/4, 0

D.) 1/4, 1/4

3.) Suppose X is time to take a bar exam where X is from 0 to 8 hours where f(x) = x/32. Find the mean of X.

Group of answer choices

A.) None of the other choices is correct

B.)5.33 hours

C.)4 hours

D.) 1 hours