The first round interview case study is VERY basic, so much so that it is hard to revise for it as all examples you come accross will be much more in depth. Its basically about 6 sentances long- it'll be a business that is having difficulties- ie needs consulting help and you will need to chip in with your thoughts as to diagnosis- Why and What are the problems and then asked to provide a few solutions. I have to stress that your solutions will only have to be simple- they just want to check you have some inititave etc, not for you to provide a statistical answer which gives your recommendations for the next 10 years. I'm from a non-business background and recommend that the only thing you need to sharpen up on is common sense.