The PO2 after two chambers at the same depth are opened to each other, weighted by their volumes.
The formula: Weighted by volume. Change any box and the full working updates. For study only, never for dive planning.
The IMCA ADS, BDS and LST papers ask this as a four-option question, with a calculator on screen. A free account gives you 15 practice questions for each exam, each with the worked answer and the document it comes from.