"In how much time have you to do the homework?"

Hello!
I'd say: "how long do you have to do the homework?"
"how much time?" is not correct, you have to say "how long?"

Yes, so would I in a less-than-formal context, but I wanted a very formal construction.

<"how much time?" is not correct, you have to say "how long?">

Why?

because time is a duration, not a quantity...

But, isn't time perceived in both ways?

How many minutes?

How long will you be?

How much time have we got?

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Here it works for me:

Student 1: ****! That was the teacher calling. I have to do the homework after all.

Student 2: Bad news. In how much time?


So why do posters say it isn't grammatical in the form be

Yes, but in your first post, you had written: "in how much time... ?
So, it's either
"how much time do we have...?" (quantification)
or
"how long do we have... ?" (length of time).
I personally wouldn't say IN how much time... But then I may be wrong...

or perhaps "in how much time do we have to hand in our homework?"

What about:
How much time do you need to do your homework?

I still prefer "how long do you need to do your homework?"
Here you are asking about the length of time it takes to do/complete the home work, right? Not about when you have to give it/hand it in.

Hello Pieanne

I'm sorry to meddle in your discussion, but I feel some difference between the two:
(1) In how much time do you need to do the homework?
(2) How long do you need to do the homework?

(1) sounds like asking the due-time to finish the homework.
Jean : "In how much time do you need to finish the work?
Anne: "Within two days"