How many table tennis balls are there in china?

And the answer was:

The candidate is not expected to produce the correct answer to the question. The purpose of it is to see how the candidate reacts under pressure, how the candidate uses logical deduction to estimate an answer. It is also important to show spacial awareness and causality.

The answer I gave outlined what I would do if I had the tools necessary to find the exact answer (i.e., using market share of major manufacturers, population data, etc). However, should I have to estimate, I would assume that since table tennis is the most popular sport in china, and that the adult population of the country is approaching 1.3 billion, that at least 13 million (10%) of the population actively play table tennis. Since table tennis balls are sold in packs of four, and that every active table tennis player in china is likely to have a least 1 pack of table tennis balls, I would estimate there to be at least 52 million table tennis balls plus balls attributable to part-time players and balls in stock inventory.

Additional information

This was asked for an operations role.