This was a previous Interview Question for Oxbridge Economic Applicants. Here is a sample answer I came up with.

To start with to answer this question it depends on how we are measuring size and successfulness. If we measure both in terms of profit then obviously a large firm (one which has larger profits) will be more successful when we say that large profits = successfulness. Similarly if we measure size in terms of output, labour force or number of shops/factories and successfulness by revenues then we would expect larger firms to have larger revenues (and thus be more successful) because they have the ability to sell more through their stores (which we are assuming they have more of to be considered large) and will be able to produce more due to their larger workforce. [...]

Two trains are about to crash. One contains pensioners and the other containers commuters. There is a fault on both lines but you can save one group. Which do you save and why?

This was a previous question asked at an Oxbridge interview. It is more of a philosophical question than it is economic and rather than give a conclusion I will present some points below as to the advantages of saving one group over the other. Please note that the argument isn’t intended to cause offence and I completely understand that each life is very precious and no-one should be prioritised (this is completely hypothetical!!!). [...]

I would define a rational being as someone that aimed to maximise the utility whilst trying to minimise the costs. Addiction is something that people do because, a. they enjoy doing it, and b. there may be psychological or chemical reactions occurring that increase the cost of not consuming the good/service.

Therefore I would believe addiction to be rational because people generally do it because they enjoy doing it and thus it maximises their utility. However because they are addicted to it perhaps they are doing it many times, and this may result in the marginal utility gained decreasing over time. [...]