for three hours vs three hours

Dear native English speakers,
I'm sorry to ask a lot of questions, but would anyone answer another question?

Would both the sentences be used?
(a) My sister watches TV for more than three hours every day.
(b) My sister watches TV more than three hours every day.

Thanks in advance.

Hirashin

Yes. Both would be used. Sentence a is better, though.

Sentence b probably should not be used by non-native English speakers with a non-native accent because it could either be used by a very casual speaker or by a non-native speaker. If I heard a native English speaker say it I would not notice it, but if I heard a non-native English speaker say it I would notice it.