1. The problem statement, all variables and given/known data Q. Given that the population of Mumbai is about 13,000,000. Estimate the amount of tea that would be consumed by the city in a day? 2. The attempt at a solution Now at first place I could not understand why such kind of a question is given in Astronomy Olympiad. May be they wanted to check our ability to do approximate estimation because in Astronomy and Astrophysics we have to estimate many different variables. For example, given the mass of a galaxy and average mass of a star estimate the number of stars in a galaxy. Regarding the above question my calculation showed nothing elegant but the necessity of 'percentage' as a mathematical tool. I don't know what did they expect. I saw chapters on estimation in books on statistics. Should I have included some statistical interpretation. And if so then how? I am expecting a question on estimation this year too. Therefore can somebody provide me with such questions and the approach of the solution so that I can have a good practice before the exam.