9X square root of tyre press in PSI. Not rocket science and covered in GCSE physics double and single award syllabus.
The number of candidates that are asked "what is meant when the aircraft is stalled?" and answer "the engine stops" is, frankly, enougth to make you bang your head against a brick wall. It's all out there. Not a secret that requires £90,000 to gain access to. No excuse not to know. ITCZ, ever studied geography?
If they seem a struggle, perhaps you should question your motivation to see the dream through.
Good luck!
