What happens to chamber PO2 when you vent to a shallower depth, or blow down deeper on a known mix.
The formula: Vent: PO2 x Pnew/Pold. Blowdown: + depth added/10 x fraction. 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.