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475.When the Sequence Stops Falling

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expected valueCh. 6 — Random Variables and Expectation444+ Problems in Probability
Let X1,X2,X_1, X_2, \dots be IID with a continuous distribution, and let NN be the first index nn such that X1X2Xn1X_1 \ge X_2 \ge \cdots \ge X_{n-1} but Xn1<XnX_{n-1} < X_n — the time the sequence first stops decreasing. Find E[N]E[N].

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