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#1 2013-12-28 05:39:36

MERTICH
Member
Registered: 2013-12-01
Posts: 18

I Ca'nt Figure Out If This Is An Exponential Question

Gordon is evaluating some stocks he wants to purchase. You can see the function of the stock price below. The variable x represents days.

Stock
A: f(x) = 25(1.08)x   
B: x    f(x)
    0    22.00
    1    21.56
    2    21.13   
C: The initial price of this stock is $30, but it has been increasing 4% each day.

1.) Create the price function for Stock D. It should have the second lowest starting price and the second highest rate of growth. Using complete sentences, justify that your function meets these requirements.
2.) Graph the price function for Stock D. Explain the key features of the graph wit

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#2 2013-12-28 05:45:39

MERTICH
Member
Registered: 2013-12-01
Posts: 18

Re: I Ca'nt Figure Out If This Is An Exponential Question

y(t) = a × ekt :

SO SHOULD THE FUNCTION BE    y=30 x e^1.2x,

where 30 is the start price, and 1.2 is 0.4 % of $30, and x number of days?

OR,  y = 30 + 1.2x

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#3 2013-12-28 06:10:39

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: I Ca'nt Figure Out If This Is An Exponential Question

Hi;

Neither of those equations fits the data you are given.

B shows the stock going down not up?!


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.

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#4 2013-12-28 06:13:00

MERTICH
Member
Registered: 2013-12-01
Posts: 18

Re: I Ca'nt Figure Out If This Is An Exponential Question

bobbym wrote:

Hi;

Neither of those equations fits the data you are given.

So how should I go about it, pliz help..

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#5 2013-12-28 06:14:27

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: I Ca'nt Figure Out If This Is An Exponential Question

Hi;

I would love to help but I can not make heads or tails of what you want.

C: The initial price of this stock is $30, but it has been increasing 4% each day.

But B shows the stock going down not up?!


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.

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#6 2013-12-28 06:21:21

MERTICH
Member
Registered: 2013-12-01
Posts: 18

Re: I Ca'nt Figure Out If This Is An Exponential Question

A ,B and C are separate kinds of stocks with different prices. That is the way I see it. Now THEY WANT STOCK D .

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#7 2013-12-28 06:25:59

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: I Ca'nt Figure Out If This Is An Exponential Question

Which is stock D and how is it related to A,B and C?


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.

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#8 2013-12-28 06:29:21

Bob
Administrator
Registered: 2010-06-20
Posts: 10,053

Re: I Ca'nt Figure Out If This Is An Exponential Question

Please clarify stock A function.

Bob

ps.  there are 4 stock functions.  The function for D is governed by the statement

It should have the second lowest starting price and the second highest rate of growth. Using complete sentences, justify that your function meets these requirements.


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#9 2013-12-28 06:37:52

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: I Ca'nt Figure Out If This Is An Exponential Question

Hi;

I agree, something is wrong with A).

B) looks linear, 2 y + .87 x = 44 fits almost exactly. Unless you are required to fit some other type of function, I would go with the simplest fit which is linear.


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.

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#10 2013-12-28 06:38:39

MERTICH
Member
Registered: 2013-12-01
Posts: 18

Re: I Ca'nt Figure Out If This Is An Exponential Question

bob bundy wrote:

Please clarify stock A function.

Bob

ps.  there are 4 stock functions.  The function for D is governed by the statement

It should have the second lowest starting price and the second highest rate of growth. Using complete sentences, justify that your function meets these requirements.

The  Price for Stock A is given by the function y= 25(1.08)x, where x is the number of days, 1.08 the rate of growth, and 25 the start price

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#11 2013-12-28 06:49:43

Bob
Administrator
Registered: 2010-06-20
Posts: 10,053

Re: I Ca'nt Figure Out If This Is An Exponential Question

That's not the way to show the function for A.  But no matter; we have enough information to answer the question.

(i) List the start values.

(ii) Identify the growth rates.  We don't have to find a function for B and as it is decreasing we can dismiss it for the question.

(iii) Choose a starting value and growth rate to suit D.  It looks like many answers are possible.

Bob

edit.  I think this is really just a question about functions and graphs.  The 'stock rates' is just window dressing.

Last edited by Bob (2013-12-28 06:52:22)


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#12 2013-12-28 06:57:29

MERTICH
Member
Registered: 2013-12-01
Posts: 18

Re: I Ca'nt Figure Out If This Is An Exponential Question

bob bundy wrote:

That's not the way to show the function for A.  But no matter; we have enough information to answer the question.

(i) List the start values.

(ii) Identify the growth rates.  We don't have to find a function for B and as it is decreasing we can dismiss it for the question.

(iii) Choose a starting value and growth rate to suit D.  It looks like many answers are possible.

Bob

edit.  I think this is really just a question about functions and graphs.  The 'stock rates' is just window dressing.

22<Dstartprice<25, and it's difficult to figure out the growth rate for B, though I can tell that stock fell by 44c, then 43c, may be 42, 42......

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#13 2013-12-28 07:07:21

Bob
Administrator
Registered: 2010-06-20
Posts: 10,053

Re: I Ca'nt Figure Out If This Is An Exponential Question

You can forget about B as it's growth rate is negative.  D has to have the second highest so it must be between A and C.

It could be exponential but no need to involve 'e'.  Once you've chosen a rate you can write the function as a power function.

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#14 2013-12-28 07:18:20

MERTICH
Member
Registered: 2013-12-01
Posts: 18

Re: I Ca'nt Figure Out If This Is An Exponential Question

Thank you guys! I really appreciate

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#15 2013-12-28 07:21:58

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,049

Re: I Ca'nt Figure Out If This Is An Exponential Question

B looks something like 22*0.98^x, but, as Bob said, it does not matter, because it is not even the second highest.


“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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