By Jen Goodman

Interviewers will want to know, first and foremost, whether you have the analytical capability and marketing knowledge to run a brand. Case questions will vary in their breadth or specificity - some may be more geared toward figuring out how an applicant formulates long-term strategy, while others will require candidates to price potential promotions. Interviewers want to hear what questions you might ask, what hypotheses you might create and what plan of action you will suggest.

When answering a case question, you must reason out loud. Take a minute or two to map out the question and to organize it in your mind but then begin a dialogue with them. The 4 Cs and 5 Ps are a great way to ensure that you've touched on all key points. Don't openly refer to the framework, however. Beginning an analysis with "Well, the first 'P' is product" will not impress your interviewer. Use the frameworks without being obvious. ~

This is a typical "how to grow a market" question. Interviewers will be most interested in the questions you ask, the assumptions you make and your intuitive understanding of the market forces at work. Don't worry if you don't know how many Christmas trees are currently sold each year, what percent of people keep them in their homes, etc. The interviewers don't expect you to know this information. The most important thing to do is to take the interviewer through your thought process by thinking aloud. You don't realize how many decisions and assumptions you may be making in your head. Don't do yourself a disservice by not voicing those assumptions during the interview. The best way to answer this type of question is to just brainstorm out loud. Breadth of answers is more important than depth in these types of "wacky" market size questions.

A good place to start would be to "brainstorm" ways to help the market grow. Could you increase the seasonality of X-mas trees? How would you do this? Perhaps start an ad campaign that would find alternate uses for the trees (like a great Valentine's Day gift). Perhaps you would work with R&D to determine if there is a way to make Christmas trees last longer or last in hot weather so that they could also be bought as a "summer plant." Zany answers, but at least you are demonstrating creativity and logic. ~

Brainstorm for your interviewer.

Could you make trees appeal to a bigger consumer target? Perhaps you could "package" trees in the latest fashion packaging so suddenly, young teenagers really want to buy one. Or, you could make trees "collectible" by selling them in five different colors - maybe people will want to collect a whole set of them.

Could you cut the price? Suggest doing a sensitivity analysis to determine how many people don't buy trees because they are too expensive or how many people would buy trees if the cost was lower.

Could you eliminate any competitive threats? One way to increase market share is to get rid of the competition. Is there any competition now? Are people using plastic trees as a substitute for the real thing? Perhaps you could create an awareness campaign that told consumers about the benefits of having a fresh tree vs. a fake one. If done effectively, this could thwart the competition and build your market share. ~

Could you make the trees more accessible? This argument is all about distribution. The reason why trees are not selling currently is because there are no outlets that are selling them. If you are not driving down a certain street during a certain time of the year, you might never see Christmas trees being sold. Why not put a tree shop on EVERY corner for the entire month of December as opposed to just the last two weeks. That should definitely build your market share.

Jennifer Goodman is a marketing specialist at McKinsey & Company and graduate of Harvard Business School.