Fermi Exercise: Sizing Daily Travel Volume Across India

Estimate how many people travel in India on a given day. Walk through how you structure the estimate, label each assumption, and finish with a figure and how confident you are in it. ```hint Pick a side to build from Decide whether you will start from how often people in India take trips or from how many passengers the rail, road and air networks move each day, and keep the other side for a cross-check. ``` ### Clarifying Questions - Does a traveler include someone commuting within their own city, or only someone going from one city, town or village to another? - Are we counting distinct people who travel that day, or one-way trips started that day? - Should international arrivals and departures count alongside domestic travel? - Is this an average day across the year, or a peak day such as a major festival period? ### What a Strong Answer Covers - A definition of who counts as a traveler, and whether the unit is people or trips, settled before any arithmetic - A top-line equation linking India's population, or its transport capacity, to daily travelers - Segments that reflect real differences in how often groups of people travel, each with a labeled, round assumption and a short rationale - Correct, unit-consistent arithmetic, including the step from yearly to daily figures - A cross-check from a second angle, a final range, and how the figure would move under a broader definition ### Follow-up Questions - Which single assumption moves your answer the most, and what data would you use to tighten it? - How would your estimate change for the busiest travel day of the year, and how would you size that peak? - If Google wanted to use this figure to size an opportunity for a travel product, which slice of it would matter and why?