Past exam of the mathematics course of the University of Cambridge 2009 ii Paper 2 27J b Solution Created 2026-09-24 Updated 2026-10-14
Take when no record has occurred below , the needed convention for the maximum of an empty set. Assume and write . Given the latest record , the chance that the next one exceeds is . Multiplying this by the joint density from part (a) leaveson the ordered simplex . Its integral is , where . The probability is directly . HenceThis is Poisson record counts in cumulative hazard coordinates; the instantaneous rate is the original distribution's hazard function. If the distribution has a finite upper endpoint and reaches it, and infinitely many record values lie below almost surely; there is then no finite-parameter Poisson law. The finite-hazard assumption is thus necessary for the literal assertion.