Questions & Answers about Dziesięć procent ludzi twierdzi, że to prawda.
Why is the verb twierdzi (claims) in the singular form when it refers to a plural group of people?
In Polish, when a subject is a quantity of five or more (like dziesięć), the verb takes the third-person singular form. Even though we are talking about multiple people, the grammatical focus is on the single block of quantity, so we say dziesięć procent twierdzi instead of the plural twierdzą.
Why is it ludzi instead of the basic plural ludzie?
Ludzi is the genitive plural of ludzie (people). Just like in English where you say "ten percent of people", Polish uses the genitive case after numbers of five or more and after units of measurement like procent.
How would this sentence change if I wanted to say "Some people claim" using niektórzy from this lesson?
Unlike quantities, niektórzy (some/certain people) behaves as a normal plural subject. You would say Niektórzy ludzie twierdzą... (or simply Niektórzy twierdzą...). Notice how the verb must switch to the plural form twierdzą, unlike the singular form used with dziesięć procent.
The English translation says "it is true", but isn't prawda a noun meaning "the truth"?