Cups of tea sold per day in a large city

The prompt

Estimate how many cups of tea are bought and sold outside the home in a large Indian city, such as Bengaluru, on a typical day.

Extra context you can assume

• State your assumptions out loud and keep the arithmetic simple.
• You may segment the population however you like.

A strong answer usually covers

• Start from the population and narrow to people who buy tea outside the home.
• Segment by frequency (daily / occasional / never).
• Multiply, then sanity-check against another approach (e.g. number of tea stalls × cups per stall).
• State your assumptions and your uncertainty.

This scenario is fictional and made up for practice.