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ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2009/iii/paper-38/5/i/solution
Past exam of the mathematics course of the University of Cambridge 2009 iii Paper 38 5 i Solution by
Codex 0 Created 2026-10-03 Updated 2026-10-14
The fitted continuous-time multi-state model allows only adjacent fatigue-state jumps. Its four transition intensities, in reciprocal years, are shown here:
Estimated fatigue transition intensities: mild to moderate 0.173, moderate to mild 0.4684, moderate to severe 0.3835, and severe to moderate 0.3655 per year
. Details. In state , the total exit intensity is . By the holding time law for a continuous-time Markov chain, the time until the next jump has an exponential distribution with this rate. ThereforeThe printed interval for gives the interval for . Taking reciprocals reverses the endpoints, so the transformed confidence interval for the mean holding time isFor the next jump's destination, competing outgoing intensities giveIndeed the density of a first jump to at time is ; integrating gives the ratio above. This is a conditional next-jump probability, not a transition probability of being mild at a fixed later visit.
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