After the initial IQ test and HR phone interview, I had a behavioral interview and a case interview.
The Behavioral Interview:
They asked only 4 major questions...asked me to describe a certain situation and then pecked at it from all sides. Have your stories clear, and the situations should be "rich", in the sense that it should have shown your leadership, initiative, how you worked with people, issues that you faced and how you overcame these issues.
The Case Interview:
You run an oil refinery that can process 1 million barrels of crude oil per year, have certain fixed costs (debt repayment, salaries, maintenance, etc), and certain variable costs (cost of crude oil, transport). You have 3 products that you sell after refining the crude oil: a certain % goes into Gasoline (highest price), another part is Heating Oil (mid-price) and finally Asphalt (lowest price).
The first question is to calculate the total profit. Simple enough - list down all revenue and cost drivers in a table and do the math.
Next they asked how would I increase the profit...hit all the cost drivers and how you would bring down those costs, then talk about how you could change your production mix towards more of the higher-priced products.
The last question presented two more options - other varieties of crude coming to the market, and with different crude prices as well as different final product mix that you could make from the crude oil varieties. Essentially the lower priced crude could make less Gasoline, and the higher priced crude could make more Gasoline. Do the profit calculations in the form of a table (with all 3 crude varieties in the table), and finally decide which variety of crude gives the highest profit. In my case, the cheapest variety of crude oil gave the highest profit, but this may be different in your case.