A Google Interview Question

I recently interviewed with Google for a product manager position. I wasn’t really looking since I have been actively working on my startup. But since the Google recruiter found me on LinkedIn and reached out to me, I went ahead and gave the whole interview process a shot. Overall, the process was professional and well organized. I thought I answered most of the questions well except for this one:

For any given day, calculate the total number of miles traveled by all the passengers using the subway.

Just want to share this!