I'm not sure if it's possible to work out, I can't quite get my head around it, and that annoys me because I have an A at A level in maths and this seemingly simple problem is way beyond me. I want to know if there is a 92.9% chance you achieve something by belonging to group A and there's a 94% chance you achieve it by belonging to group B and it is possible to belong to both groups (but the value of how many people belong to each or both is unknown), what is the percentage chance of someone in both groups NOT achieving. For example 92.9% of people who do sports get an award and 94% of people who play a musical instrument get the same award what is the probability of someone who plays both sport and an instrument NOT achieving the award? I'm not sure if this makes any sense...and I'd appreciate if nobody just wrote the answer, I'd like to know what calculations you'd have to do and why so I can understand the answer. Is it possible to work this out? Thanks