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The National Basketball Association (NBA) draft lottery involves the 11 teams that had the worst won—lost records during the year. A total of 66 balls are placed in an urn. Each of these balls is inscribed with the name of a team: Eleven have the name of the team with the worst record, 10 have the name of the team with the second-worst record. 9 have the name of the team with the third-worst record, and so on (with I ball having the name of the team with the 11th-worst record). A ball is then chosen at random, and the team whose name is on the ball is given the first pick in the draft of players about to enter the league. Another ball is then chosen, and if it belongs to a team different from the one that received the first draft pick, then the team to which it belongs receives the second draft pick. (If the ball belongs to the team receiving the first pick, then it is discarded and another one is chosen: this continues until the ball of another team is chosen.) Finally, another ball is chosen, and the team named on the ball (provided that it is different from the previous two teams) receives the third draft pick. The remaining draft picks 4 through 11 are then awarded to the 8 teams that did not win the lottery, in inverse order of their won—lost records. For instance, if the team with the worst record did not receive any of the 3 lottery picks, then that team would receive the fourth draft pick. Let X denote the draft pick of the team with the worst record. Find the
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A First Course in Probability
- Total marks 14 4. Let X and Y be random variables on a probability space (N, F, P) that take values in [0, ∞). Assume that the joint density function of X and Y on [0, ∞) × [0, ∞) is given by f(x, y) = 2e-2x-y Find the probability P(0 ≤ X ≤ 1,0 ≤ y ≤ 2). (ii) spectively. [6 Marks] Find the the probability density function of X and Y, re- [5 Marks] 111) Are the X and Y independent? Justify your answer! [3 Marks]arrow_forwardTotal marks 17 4. Let (,,P) be a probability space and let X : → R be a ran- dom variable that has Gamma(2, 1) distribution, i.e., the distribution of the random variable X is the probability measure on ((0, ∞), B((0, ∞))) given by (i) dPx(x) = xex dx. Find the characteristic function of the random variable X. [8 Marks] (ii) Using the result of (i), calculate the first three moments of the random variable X, i.e., E(X") for n = 1, 2, 3. Using Markov's inequality involving E(X³), (iii) probability P(X > 10). [6 Marks] estimate the [3 Marks]arrow_forward1. There are 8 balls in an urn, of which 6 balls are red, 1 ball is blue and 1 ball is white. You draw a ball from the urn at random, note its colour, do not return the ball to the urn, and then draw a second ball, note its colour, do not return the ball to the urn, and finally draw a third ball, note its colour. (i) (Q, F, P). Describe the corresponding discrete probability space [7 Marks] (ii) Consider the following event, A: At least one of the first two balls is red.arrow_forward
- 3. Consider the following discrete probability space. Let = {aaa, bbb, ccc, abc, acb, bac, bca, cab, cba}, i.e., consists of 3-letter 'words' aaa, bbb, ccc, and all six possible 3-letter 'words' that have a single letter a, a single letter b, and a single letter c. The probability measure P is given by 1 P(w) = for each weΩ. 9 Consider the following events: A: the first letter of a 'word' is a, B: the second letter of a 'word' is a, C: the third letter of a 'word' is a. answer! Decide whether the statements bellow are true or false. Justify your (i) The events A, B, C are pairwise independent. (ii) The events A, B, C are independent. Total marks 7 [7 Marks]arrow_forwardLet X and Y have the following joint probability density function: fxy(x,y) =1/(x²²), for >>1, y>1 0, otherwise Let U = 5XY and V = 3 x. In all question parts below, give your answers to three decimal places (where appropriate). (a) The non-zero part of the joint probability density function of U and V is given by fu,v(u,v) = A√³uc for some constants A, B, C. Find the value of A. Answer: 5 Question 5 Answer saved Flag question Find the value of B. Answer: -1 Question 6 Answer saved P Flag question (b) The support of (U,V), namely the values of u and vthat correspond to the non-zero part of fu,v(u,v) given in part (a), is given by:arrow_forwardTotal marks 13. 3. There are three urns. Urn I contains 3 blue balls and 5 white balls; urn II contains 2 blue balls and 6 white balls; urn III contains 4 blue balls and 4 white balls. Rolling a dice, if 1 appears, we draw a ball from urn I; if 4 or 5 or 6 appears, we draw a ball from urn II; if 2, or 3 appears, we draw a ball from urn III. (i) What is the probability to draw a blue ball? [7 Marks] (ii) Assume that a blue ball is drawn. What is the probability that it came from Urn I? [6 Marks] Turn over. MA-252: Page 3 of 4arrow_forward
- 3. Consider the discrete probability space with the sample space = {a, b, c, d, e, f, g, h} and the probability measure P given by P(w) for each wEN. Consider the following events: A = {a, c, e, g}, B = {b, c, d, e}, C = = {a, b, d, g}. Decide whether the statements bellow are true or false. Justify your answer! (i) The events A, B, C are pairwise independent. (ii) The events A, B, C are independent. Total marks 6 [6 Marks]arrow_forward2. space Consider the discrete probability space (N, F, P) with the sample N = {W1 W2 W3 W4 W5, W6, W7, W8, W9, W10, W11, W12}, is the power of 2, and the probability measure P is given by 1 P(wi) for each i = 1, 12. 12 Consider the following events: A = {W1, W3, W5, W7, W9, W11}, C = B = {W1, WA, W7, W8, W9, W12}, = {W3, WA, W5, W6, W9, W12}. Decide whether the statements bellow are true or false. Justify your answer! (i) The events A, B, C are pairwise independent. [5 Marks] Total marks 8 (ii) The events A, B, C are independent. [3 Marks]arrow_forwardshould my answer be 2.632 or -2.632?arrow_forward
- 2. Alice has three unfair coins. The first coin shows heads with proba- bility 0.3 and tails with probability 0.7. The second coin shows heads with probability 0.9 and tails with probability 0.1. The third coin shows heads with probability 0.4 and tails with probability 0.6. First, Alice throws a dice. If the dice yields a 1 or 2, Alice tosses the first coin. If the dice yields a 3, Alice tosses the second coin. If the dice yields a 4 or 5, or 6, Alice tosses the third coin. (i) What is the probability of the following event: as a result of throwing the dice and then tossing a coin, tails appear. [7 Marks] Assume a coin shows tails. What is the probability that Alice (ii) tossed (a) the first coin; (b) the second coin; Total marks 11 (c) the third coin? [4 Marks]arrow_forwardIn a Poisson process with A = 500 arrivals per day, find the approximate probability that the thousandth arrival comes between 47.5 and 48.5 hours after the start of observations.arrow_forwardSuppose you generate 300 independent observations X1, ..., X300 from a Uniform(0,3) distribution. a) What is the approximate distribution of X? b) What is the approximate probability that X is less than 1.57? c) What is the approximate probability that the sum S300 = X₁++X300 is between 442 and 483?arrow_forward
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