Determine the value of c that makes the function f(x, y) = c(x + y) a joint probability density function over the range 1

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Extracted text: Determine the value of c that makes the function f(x, y) = c(x + y) a joint probability density function over the range 1 < x="">< 4="" and="" 0="">< y="">< 3="" а.="" c="24" o="" b.c="24" o="" c.="" none="" od.="" c="">


Extracted text: Suppose the log-ins to a company's computer network follow a Poisson process with an average of three counts per minute. What is the mean time between counts? What is the standard deviation of the time between counts? O a. NONE O b. E(X) = 3, SD(X) = 3 O c. E(X) = 0.333, SD(X) = 0.333 O d. E(X) = 0.333, SD(X) = 0.111