Hi FRA,i just had my 3rd stage interview yesterday, by a manager.it was the most difficult process, i would say. the cases were fine and doable but the interviewer made the whole thought process difficult by scrapping and challenging most of the assumptions used. my analysis is : i think the interviewer wanted to test whether i was a TCUP material (think clearly under under pressure).the 1st case was on the number of fixed phone in a country i knew very little about.i divided the phone lines to residential and business lines. assumed urban-ratio population breakdown of 40-60 and break the assumed national population based on that ratio. thereafter, i broke down the the population with household ratio ratio of 1:10 and 1:5 for rural and urban areas respectively. thereafter, i assumed that phone household penetration in urban is 100% while in rural area is 60%. following that you will get the phone lines for residential.as for business, it is a bit complicated as you need to go through the list of working population, then the industry, then % of phone penetration. he discarded my initial snapshot approach of basing the number on SMEs and businesses. in the process, the interviewer kept on asking me to change the approach and assumption.the 2nd was on a problem faced by a steel manufacturer on rising raw material cost. i structured the approach by [1]analysing the problem i.e. the type of raw material, rate of increase, trend, % of manufacturing cost[2] industry, i.e. customer, economics, competitor[3] the profitability function the interviewer then asked me to give 5 potential solutions, he did not give me the time to structure and gained mental composure on this. he wanted me to write and think-loud the solution there and then. i gave 8 and 3 got marked down as not acceptable [such as raising prices and improvements of manufacturing process] as those had already been implemented by the company. the solutions include acquisitions of suppliers, branching out into other businesses (as this raw material represents 50% of manufacturing cost, the rate of rise has been 30% and was expected to continue, the rise was due to huge demand for from steel companies companies in China due to massive construction growth over there, local demand for the company's steel product has been stagnant), use of substitute raw materials, formation of consortium of steel manufacturers for better mileage in negotiation with the suppliers etc.all the best to you.