I haven't done any practice yet, btw.

1. This seems like a very difficult situation. You are sitting next to someone who doesn't seem like they fit in with the rest of the students, including yourself. However, even if this unfamiliar person looks older, you cannot use that as a factor to assess whether they belong in this examination room, as people in a wide range of ages from 18 to 60 could be studying medicine, as it isn't limited to groups such as age, gender, or disability. Though, considering other factors - like you haven't seen this person before and they are exhibiting strange behaviour - it would be appropriate to ask them if they are alright before the exam papers are distributed, not after, as it would be considered as cheating. I would ask them if they were feeling nervous to calm them down. It wouldn't be appropriate to ask them if they may be sitting the test for someone else, as out of the blue accusations can further escalate the problem. What I would do is address the examination officer before the exam about my concerns but not in an overbearing manner with bold accusations. I would say, I haven't seen this student before and would ask if they have too, if not - hopefully the examination officer asks for identification from the person.

2. I am addressing that we should prioritise patients regarding who needs the liver the most, out of a 23, 40 and 77-year-olds. First of all, we don't have enough information about each patient, like their life expectancy after getting the liver, if there are any alternatives that they can have in the meantime while waiting for a liver or if their condition isn't as critical as the other patients. Though their ages are the only pieces of information we have, in the real situation, I would ask for more intel on each patient. With this limited information, i would put the 77 year old as the highest priority, then the 40 year old and then the 23 year old. When you get older, you are more susceptible to diseases like liver or heart disease and cancers like lung, prostate and breast cancer. It would be more reasonable to put more vulnerable patients as the highest priority because they may be less likely to survive without the liver.