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#1 2018-02-04 00:20:08

Hannibal lecter
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Registered: 2016-02-11
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the largest interval on the following table

Hi,

The table shows the recent annual percent growth in US biodiesel consumption

2018_02_04_151626.png

find largest time interval over which the percentage growth in the US consumption of biodiesel was an increasing function of time


I found the answer is :  largest interval was 2008–2009 since the percentage growth rate increased from−11.7 to 7.3
(Note that the percentage growth rate was a decreasing function of time over 2005–2007.)



but why it's not from 2005 - 2006?
which gives  237 to 186.6 , isn't that the largest interval

Last edited by Hannibal lecter (2018-02-04 00:29:38)


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#2 2018-02-04 00:29:19

Hannibal lecter
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Registered: 2016-02-11
Posts: 187
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Re: the largest interval on the following table

and the second question is : Q2)  Find the largest time interval over which the actual US consumption of biodiesel was an increasing function of time. Interpret what increasing means, practically speaking, in this case.

I found the answer is for Q2 :-

The largest time interval was 2005–2007 since the percentage growth rates were positive for each of these three consecutive years. This means that the amount of biofuels consumed in the US steadily increased during the three year span from 2005 to 2007, then decreased in 2008


that don't make any sense? the first answer of Q1 say the largest interval is from 2008-2009
and the second answer for the Q2 said that the largest interval from 2005-2007? as well as it'a a decreasing function not increasing! ( over this interleave )


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#3 2018-02-04 01:04:19

zetafunc
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Registered: 2014-05-21
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Re: the largest interval on the following table

Hannibal lecter wrote:

Hi,

The table shows the recent annual percent growth in US biodiesel consumption

https://preview.ibb.co/kDyByx/2018_02_04_151626.png

find largest time interval over which the percentage growth in the US consumption of biodiesel was an increasing function of time


I found the answer is :  largest interval was 2008–2009 since the percentage growth rate increased from−11.7 to 7.3
(Note that the percentage growth rate was a decreasing function of time over 2005–2007.)



but why it's not from 2005 - 2006?
which gives  237 to 186.6 , isn't that the largest interval

The key word here is that we want to find the largest time interval where the percentage growth was an increasing function of time. Imagine plotting a graph with years on the x-axis and percentage growth on the y-axis -- what would it look like?

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#4 2018-02-04 01:07:40

zetafunc
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Registered: 2014-05-21
Posts: 2,179
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Re: the largest interval on the following table

Hannibal lecter wrote:

and the second question is : Q2)  Find the largest time interval over which the actual US consumption of biodiesel was an increasing function of time. Interpret what increasing means, practically speaking, in this case.

I found the answer is for Q2 :-

The largest time interval was 2005–2007 since the percentage growth rates were positive for each of these three consecutive years. This means that the amount of biofuels consumed in the US steadily increased during the three year span from 2005 to 2007, then decreased in 2008


that don't make any sense? the first answer of Q1 say the largest interval is from 2008-2009
and the second answer for the Q2 said that the largest interval from 2005-2007? as well as it'a a decreasing function not increasing! ( over this interleave )

Because the table refers to percentage growth. If it grew by a positive percentage in 2005, 2006 and 2007, then the biodiesel consumption was still increasing in those years, but it was just growing more slowly in 2007 compared to 2006 and 2005.

The biodiesel consumption decreased in 2008, because its percentage is negative. Then it grew a little bit in 2009, because the percentage is positive.

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#5 2018-02-07 07:16:50

Hannibal lecter
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Registered: 2016-02-11
Posts: 187
Website

Re: the largest interval on the following table

zetafunc wrote:
Hannibal lecter wrote:

Hi,

The table shows the recent annual percent growth in US biodiesel consumption

https://preview.ibb.co/kDyByx/2018_02_04_151626.png

find largest time interval over which the percentage growth in the US consumption of biodiesel was an increasing function of time


I found the answer is :  largest interval was 2008–2009 since the percentage growth rate increased from−11.7 to 7.3
(Note that the percentage growth rate was a decreasing function of time over 2005–2007.)



but why it's not from 2005 - 2006?
which gives  237 to 186.6 , isn't that the largest interval

The key word here is that we want to find the largest time interval where the percentage growth was an increasing function of time. Imagine plotting a graph with years on the x-axis and percentage growth on the y-axis -- what would it look like?


The largest time interval was 2005–2007 since the percentage growth rates were positive for each of these three consecutive years. This means that the amount of biofuels consumed in the US steadily increased during the three year span from 2005 to 2007, then decreased in 2008
_____________________+++++

first how it is " steadily increased during the three year" ? it's 237  to  186.6 then 37.2, how  it's increased? I see deacreainsg
second : what is the meaning of  "the actual US consumption"

because there is a two question as you saw a) and b) , the a) says  Find the largest time interval over which the percentage growth in the US consumption of biodiesel was an increasing function of time.......

and the b) says : Find the largest time interval over which the actual US consumption of biodiesel was an increasing function of time.....

can you explain these to me please


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#6 2018-02-07 07:20:10

Hannibal lecter
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Registered: 2016-02-11
Posts: 187
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Re: the largest interval on the following table

zetafunc wrote:
Hannibal lecter wrote:

and the second question is : Q2)  Find the largest time interval over which the actual US consumption of biodiesel was an increasing function of time. Interpret what increasing means, practically speaking, in this case.

I found the answer is for Q2 :-

The largest time interval was 2005–2007 since the percentage growth rates were positive for each of these three consecutive years. This means that the amount of biofuels consumed in the US steadily increased during the three year span from 2005 to 2007, then decreased in 2008


that don't make any sense? the first answer of Q1 say the largest interval is from 2008-2009
and the second answer for the Q2 said that the largest interval from 2005-2007? as well as it'a a decreasing function not increasing! ( over this interleave )

Because the table refers to percentage growth. If it grew by a positive percentage in 2005, 2006 and 2007, then the biodiesel consumption was still increasing in those years, but it was just growing more slowly in 2007 compared to 2006 and 2005.

The biodiesel consumption decreased in 2008, because its percentage is negative. Then it grew a little bit in 2009, because the percentage is positive.

so you mean it's like +%236 and +%186.6 and so on?

so it's increasing always???


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#7 2018-02-13 21:14:57

Hannibal lecter
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Registered: 2016-02-11
Posts: 187
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Re: the largest interval on the following table

or the reason is just just because there is  a negative sing in the middle of the graph


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#8 2018-02-13 21:26:46

Hannibal lecter
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Registered: 2016-02-11
Posts: 187
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Re: the largest interval on the following table

and this is a picture of the full question :-

2018_02_14_122550.png



a) answer : is 2008-2009

b) answer is :  2005-2007

can you explain to me again in other way please

Last edited by Hannibal lecter (2018-02-13 21:28:09)


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