Past exam of the mathematics course of the University of Cambridge / 2023 / iii / Paper 207 / 5 / v / Solution

At month 12, patients C and D are censored at durations 6 and 1, respectively. When B dies at duration 7, only A and B remain at risk, so

At month 36, all six patients have at least twelve months of potential follow-up unless they die earlier. The only deaths by duration twelve are B and E, tied at duration seven, so