In his early investigations, Pavlov noted that a moist, edib…
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In his eаrly investigаtiоns, Pаvlоv nоted that a moist, edible substance placed in a dog’s mouth elicited a
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Prоblem 1: Set Operаtiоns аnd Prоbаbility Rules (25 pts, 5 pts each) a) (bigcup_{n=2}^infty (n^{-n},1) = ?) b) (bigcup_{n=1}^{infty} (-frac{1}{n},frac{1}{n}) = ?) c) (Omega = {1,2,3,4}). Let (A = {1,2,4}) and (B={2,3}). If all events are equally likely, find (P(A cap B^c)). d) (Omega = {1,2,3,4}). Let (P(Omegasetminus{3}) = x) and (P({4}) = y). What is (P({3}))? e) (Omega = {1,2,3,4}). Let (P(Omegasetminus{3}) = x) and (P({4}) = y). What is (P({1,2}))? Problem 2: Bayes' Theorem (25 pts) A hospital uses a diagnostic test to screen patients for a rare disease. We use (D) as a random variable indicating if the patient actually has the disease ((D=1)) or is healthy ((D=0)). The binary random variable (T) indicates if the test is positive ((T=1)) or negative ((T=0)). The test correctly identifies 80% of the patients who have the disease, (P(T=1|D=1) = 0.8). The test incorrectly gives a positive result for 5% of healthy patients, (P(T=1|D=0) = 0.05). Please answer the following questions about this diagnostic test. a) If 5% of the population has this disease, what is the probability a patient with a positive test result actually has this disease? In other words, what is (P(D=1|T=1))? b) Say the test is improved, so now (P(T=1|D=1) = 0.01). If 5% of the population has this disease, what is the probability a patient with a positive test result actually has this disease? c) This disease is even more rare in some populations. Using the original test, what is the probability that a patient with a positive test result actually has this disease if the base rate of the disease is 1%? Problem 3: Joint and Marginal PMFs (25 pts) Roll a four-sided dice twice. Let (X) be the number of dice that show values greater than or equal to three. Let (Y) be the number of dice that are odd. a) Find the joint PMF of (X) and (Y). b) Find the marginal PMF of (X). Problem 4: Expectations of a Known Random Variable (25 pts) Let (X sim text{Geometric}(p)) with (p = 1/2). a) Evaluate (mathbb{E}[p^X]). b) Evaluate (P(X < 1/p)). Hint: Remember that (P(X in mathcal{A}) = mathbb{E}[mathbb{1}[X in mathcal{A}]]). Congratulations, you are almost done with Midterm 1. DO NOT end the Honorlock session until you have submitted your work to Gradescope. When you have answered all questions: Use your smartphone to scan your answer sheet and save the scan as a PDF. Make sure your scan is clear and legible. Submit your PDF to Gradescope as follows: Email your PDF to yourself or save it to the cloud (Google Drive, etc.). Click this link to go to Gradescope to submit your work: Midterm 1 - OUS Students Return to this window and click the button below to agree to the honor statement. Click Submit Quiz to end the exam. End the Honorlock session.