QUESTION 8 The random variable Xhas mean 3 and standard deviation 3. The random variable Y has mean -5 and standard deviation 2. The two random variables are independent. Use this information to answer Questions 8 to 11 below. What is the mean of 3X + 2Y? O a.-5 O b- -1 O CO O d- 1 QUESTION 9 What is the standard deviation of 4Y - 2X7 O a- 16.49 O b-10 O -5 O d- 8.34 QUESTION 10 Let on be the standard deviation of 2X, and oz be the standard deviation of 3Y. Which of the following is true? 0 8 01 > 02 O b. None of the above is always true. 0 601 02 O d. 01 = 02 QUESTION 11 Let X1, X2 ..., X25 be 25 independent draws from X (i.e., all of them have the same mean and standard deviation as that of X). What is the standard deviation of X1 + X2 +.. + X25? O a- 40 O b- 225 O C 15 O d- 30