Answers

Oct 07, 2017 - 01:38 AM
est-ce que is informal and is one of several ways to make a question. A question can also be as simple as making a statement with the proper inflection, like when you do that in English.
lesson 1, session 3 gets into the est-ce que and inflection stuff during the main lecture.
lesson 1, session 3 gets into the est-ce que and inflection stuff during the main lecture.

Oct 09, 2017 - 05:00 PM
You already have a "question word" in the sentence (combien), so you don't need "est-ce que". If the sentence was "nous allons être 4 persones", then the question would be "est-ce que nous allons être 4 personnes" ?

Oct 10, 2017 - 09:06 AM
Est-ce que is neither formal or informal—it's a way to construct a question phrase. You'll even see the inversion being used in French, mostly in writing such as "Avez-vous des enfants"? Or you can use "Est-ce que vous avez des enfants"?, or "Vous avez des enfants". Personally, I recommend using the "Est-ce que" when speaking. It lets the person know you are about to ask a question and gives you some time to plan the sentence too .