Math Is Fun Forum

mAX9

Member

Registered: 2010-06-01

Posts: 4

Last Big Questions After A Tiring Day Of Homework!?

Hi I'm up to the last part of the long homework we have to do. If i complete this as well I will be able to pass everything at school.

Modelling Water In A Reservoir

In the year 2001/2002 measurements taken of the volume of water in the Delmaine reservoir ('00 Megalitres) varied with time thus:

t (# months after October 1'st).:1 l 3 l 4 7
V (100's ML)..........................:7 l 6 l 5 l3

The minimum volume was found to be at t = 7

a. Find a quadratic equation of the form y = a(x-h)*squared* + K that approximately fits the data explaining carefully how you obtained the values of a, h and k.

b. Sketch the graph of the function you have obtained in part (a), over the domain [0,12].

c. According to this model, what will be the volume of water 9 months after October 1'st?

It was a long day and I need sleep, please help me out here, I really need answers to these, Thank you.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Last Big Questions After A Tiring Day Of Homework!?

Hi;

I am having trouble understanding this:

t (# months after October 1'st).:1 l 3 l 4 7
V (100's ML)..........................:7 l 6 l 5 l3

Is this what you mean?

# of Months      V(100's ML)
1                       -7
3                        6
4                        5
7                        3

I can fit any equation to that data that you want. But it is too hard to guess what you mean also. Please clarify.

It was a long day and I need sleep, please help me out here, I really need answers to these, Thank you.

I know you have been working hard. I would love to help. You have shown no work of your own. To just answer your homework is not correct for me or anyone else to do. You have not even put it into some neat form that I can understand easily.

A large portion of math is correctly stating problems and neat work. My teachers ripped the heck out of me for my lack of neatness. Do not let that happen to you.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mAX9

Member

Registered: 2010-06-01

Posts: 4

Re: Last Big Questions After A Tiring Day Of Homework!?

Yes, that's what i mean

I've done 10 parts this is the last. I just need this last one and if I don't do it I may fail the semester. Well that's what the teacher says -.-

Last edited by mAX9 (2010-06-01 03:23:00)

mAX9

Member

Registered: 2010-06-01

Posts: 4

Re: Last Big Questions After A Tiring Day Of Homework!?

Guys I need B) and C) . Hopefully I will see an answer. I seriously do need some sleep now. Thank you.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Last Big Questions After A Tiring Day Of Homework!?

Hi;

These are your equations:

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mAX9

Member

Registered: 2010-06-01

Posts: 4

Re: Last Big Questions After A Tiring Day Of Homework!?

Hi;

These are your equations:

How did you get that?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Last Big Questions After A Tiring Day Of Homework!?

Hi;

Just expanded out each equation. Now we must solve for a , h and k.

As you can see this is a non linear set of simultaneous equations. You can see that by the a*h and a*h^2 terms. This is not an easy fit. The set of equations is inconsistent also, meaning it has no solution.

There is a much easier method than that. See the answer in post #8.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Last Big Questions After A Tiring Day Of Homework!?

Hi;

There is a trick to getting the form that you require. If you need to see how I did it, just ask.

Here is b)

http://www.mathsisfun.com/graph/functio … ymax=8.026

c) You can get for yourself.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Last Big Questions After A Tiring Day Of Homework!?

That really bakes my potato

Are you actually putting any of your own effort into doing your own homework, or just waiting for nice people like bobbym to give you something for you to copy?

I have seen that you have posted this problem literally across the internet. I myself have solved it on 2 different forums. At first I thought you were familiar with the topic. But now I see that you have just been posting and deleting other posters work at me and mine at them. I addition to this being wasteful of volunteers time and effort it is also destructive to yourself.

A strong moderator I know will not work on any problem that he sees posted across multiple forums. He checks first. In hindsight I can't say that he is wrong. The first rule school must teach you is never, never ever cheat yourself. Living where I do, I have seen every hustle and every dodge. Most of them are smart enough to never cheat themselves.

Copying and posting back and forth may seem like a great idea now...

See this link for more:

http://www.mathisfunforum.com/viewtopic.php?id=13759

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.