Upon examining the child, the doctor finds a rash. What is the probability that the child has measles

A market has both an express checkout line and a superexpress checkout line. Let X₁ denote the number of customers in line at the express checkout at a particular time of day, and let X₂ denote the number of customers in line at the superexpress checkout at the same time. Suppose the joint pmf of X₁ and X₂ is as given in the accompanying table. X1 0 1 2 3 4 b. 0 .08 .06 .05 .00 .00 1 .07 .15 .04 .03 .01 X2 2 .04 .05 .10 .04 .05 3 .00 .04 .06 .07 .06 a. What is P(X₁ = 2 and X₂ = 2), that is the probability that there is exactly one customer in each line? What is P(X₁ = X₂), that is, the probability that the numbers of customers in the two lines are identical? c. Let A denote the event that there are at least two more customers in one line than in the other line. Express A in terms of X₁ and X2, and calculate the probability of event A, that is P(A). d. Determine the marginal pmf of X₁, and then calculate the expected number of customers in line at the express checkout. e. Determine the…

An education researcher claims that at most 3​% of working college students are employed as teachers or teaching assistants. In a random sample of 500 working college​ students, 4​% are employed as teachers or teaching assistants. At α=0.05​, is there enough evidence to reject the​ researcher's claim? Complete parts​ (a) through​ (e) below.       ​(a) Identify the claim and state H0 and Ha.   Identify the claim in this scenario. Select the correct choice below and fill in the answer box to complete your choice. ​(Type an integer or a decimal. Do not​ round.)   A. enter your response here​% of working college students are employed as teachers or teaching assistants.   B. At most enter your response here​% of working college students are employed as teachers or teaching assistants.   C. More than enter your response here​% of working college students are employed as teachers or teaching assistants.   D. The percentage of working college students who are…

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