It takes 1 day if you fail the test like I did. Questions are ridiculous - undergraduate material - although as already mentioned they ask you to read books about portfolio management. I do not know why G research are wasting their candidates time. I have no idea what is the point asking a PhD from a top 50 university in the world these type of questions - obviously if you have degree from Oxford or Michigan it is highly unlikely that you will not be able do understand basic maths like linear algebra or some obscure corner of statistics - the point of your good education is that you have seen these things already and you will be able to remind them in 30 mins time if necessary. If I have to be honest, nobody of the really smart people around the world remembers all details of their field - the point is to have seen them. But G research obviously would like to find somebody who can multiply 5 digit numbers in their head while doing one-arm pull ups with one hand and writing operas with the other. Good luck in finding such a PhD - but please do not lose everybody else's time.