The density of a mixture of 1.5m3 of water and 0.5m3 of alcohol of density 800 kgm–3 is:

Ibelieve the answer is going to be b

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's. 

Maybe because he failed the classes or is very accelerated.

What are the questions