"The population of the US is bigger than that of Britian, France and Germany put together."

[hardyweineberg]

"The population of the US is bigger than that of Britian, France and Germany put together."
Source: https://dictionary.cambridge.org/dictionary/english/together

I saw this sentence in the Cambridge Dictionary, but I think in the sentence, 'that' is not the correct word to use; it's 'those' since population is a countable noun. To my knowledge, this is the grammatically correct form: "The population of the US is bigger than those of Britian, France and Germany put together."

Is the dictionary's example wrong or correct?

 

[emsr2d2]

The dictionary example is correct. It considers the populations of Britain, France and Germany (for the purposes of the example) to be one population.

The "those" in your suggested version has no plural antecedent.