Past exam of the mathematics course of the University of Cambridge / 2025 / iii / Paper 207 / 3 / c / Solution

Let $n$ be the sample size in each arm, ${\pi }_{1A}={\pi }_0+{\delta }_A$, and ${\bar{\pi }}_A=({\pi }_{1A}+{\pi }_0)/2$. Solving the normal-approximation power equation givesrounded upward. The total sample size is $2n$.