Suppose that {Yt } is stationary with autocovariance function γk. (a) Show that Wt = ∇Yt = Yt − Yt − 1 is stationary by finding the mean and autocovariance function for {Wt }. (b) Show that Ut = ∇2Yt = ∇[Yt − Yt−1] = Yt − 2Yt−1 + Yt−2 is stationary. (You need not find the mean and autocovariance function for {Ut }.)

after abc its efg

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answer: i think it's a

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spinning a 1, 2, or 3. option d.

step-by-step explanation: when spinning a number graph up to 4, and aiming for any number less than 3, that automatically eliminates the number 4. now you have two numbers to spin on that are less than 3, but the number 3 is included in this question because it's no greater of an number than itself. i hope this you : )