Rec 8 - Discrete Random Variables_-1

STAT 1430 Recitation 8 Discrete R. V. PART 1 1. The number of accidents that occur at a certain intersection in a given year is a continuous random variable. a) True b) False 2. Suppose X has a distribution with mean 10 and Y has a distribution with mean 20. The mean of X – Y is 30. a) True b) False 3. Which of the following is a NOT a discrete random variable? a) The time between accidents on a busy highway. b) The number of accidents on a busy highway. c) The number of red cars that go by, in a random sample of 100. d) All of the above are discrete random variables. 4. The table below shows the probability distribution of X. What is the mean of X? a) 2.8 b) 2.85 c) 2.0 d) None of the above are correct. 5. If X and Y are random variables with μ X = 5 and μ Y = 8, then what is μ 2X-3Y ? a) -34 b) - 14 x 0 1 2 3 4 P(X = x) 0.10 0.05 0.15 0.30 0.40

STAT 1430 Recitation 8 Discrete R. V. c) 14 d) 34 6. If X and Y are random variables with μ X = 2 and μ Y = 8, then what is μ 2X+3Y ? a) 34 b) 13 c) 28 d) 40 7. Which of the follow statements is true? a) b) c) (C is the correct answer) FOR THE NEXT 3 PROBLEMS: Suppose X = the number of pets owned by a family in the U.S. The probability distribution of X is shown in the table below. 8. What is the chance that a family owns more than one pet? a) .23 b) .21 c) .44 d) None of the above are correct. 9. Suppose you choose two families at random. What is the chance that family A owns zero pets, given that family B owns zero pets? a) .0529 μ aX + b = μ bX + a μ aX = μ x + a μ X + b = μ X + b X 0 1 2 3 P(X = x) 0.56 0.23 0.12 0.09