Exam 1 Core Answers

[AhaShake]

a scatter plot would not work
you would assume that there would be atleast one case of each
as such you would get a plot that looks like the channel 9 old logo with nothing to actually show, just 9 points. dont know what percentage of high salary earners have what.
it's segmented bar charts.

[Lyonzy]

a scatter plot would not work
you would assume that there would be atleast one case of each
as such you would get a plot that looks like the channel 9 old logo with nothing to actually show, just 9 points. dont know what percentage of high salary earners have what.
it's segmented bar charts.

Agreed. I think they are just trying to confuse us by giving them numbers.

[gangreen]

but as nh4n said, you would need multiple bar charts, is that right?

[AhaShake]

you would need multiple bars within the one bar chart yes.

[gangreen]

ok got you

[nh4n]

but the fact is that, you cannot compare the two variables even if u had two segmented bar chart within the one. u cannot see if someone that has a high salary level, will have a small/medium or large car. all you are doing with 2 segmented bar charts is showing their percentages respectively, and independently, the question clearly ask for how to link the relationship between the two.. you cannot relate the two with segmented bar charts
but with a scatter plot u can, as the point (1,2) would indicate someone with a small car with a medium salary level

[joechan521]

but the fact is that, you cannot compare the two variables even if u had two segmented bar chart within the one. u cannot see if someone that has a high salary level, will have a small/medium or large car. all you are doing with 2 segmented bar charts is showing their percentages respectively, and independently, the question clearly ask for how to link the relationship between the two.. you cannot relate the two with segmented bar charts
but with a scatter plot u can, as the point (1,2) would indicate someone with a small car with a medium salary level

|3|        
|2|
|1| <--- salary
|1|
|1|

1---------2--------3 (car size)
does that graph makes sense? i only drew one bar, should be 3

[nh4n]

alright now tell me, what percentage of ppl with a small car have a high salary? cos your graph is only displaying one side, you're only telling us how much percentage of low/high/medium salary level have a small/medium/car respectively. you cannot from the graph see what percentage of ppl with a small car have a low/medium/high salary

answers can be found at http://www.itute.com/mathline/2007_vcaa_fm_exam1_sol.pdf
it says for 10: A

[Odette]

alright now tell me, what percentage of ppl with a small car have a high salary? cos your graph is only displaying one side, you're only telling us how much percentage of low/high/medium salary level have a small/medium/car respectively. you cannot from the graph see what percentage of ppl with a small car have a low/medium/high salary

answers can be found at http://www.itute.com/mathline/2007_vcaa_fm_exam1_sol.pdf
it says for 10: A

I totally agree lol

[AhaShake]

how can you tell any percentages with a scatter plot. it ONLY tells us that yes, someone with a small salary has a small car. doesnt tell us anymore.
check this graph i just made



there you go.

[nh4n]

alright ahashake, now tell me.. from your graph. what is the percentage of ppl with a low income that has a large car?, like other guy u only showing one side as well cause your only showing what percentage of low/medium/high salary earning have a small/medium/large car respectively

[nh4n]

[img]http://aycu11.webshots.com/image/30970/2005929908196050465_th.jpg[/img]
heres a scatter plot that i drew

[AhaShake]

haha that shows absolutely nothing.
only that yes, someone with income level 1 has a car of size level 2. mine shows that PLUS the percentage breakdown of what type of cars are owned by each level of salary.
what do you think yours shows?

[nh4n]

aha u still cant see that ur graph only shows one side? only showing what percentage of ppl with a small/medium/large car have a low/medium/high income, it cannot show the reverse like u cannot see from the graph what percentage of ppl with a low income have a large car, cant u see that fact?
i know the scatterplot is not perfect for displaying these 2 variables, as they are catagorial "made into" numerical. however it is the best one out of the 5 to used
once again answers are at http://www.itute.com/mathline/2007_vcaa_fm_exam1_sol.pdf
10:A

[AhaShake]

No. By your logic segmented bar charts are useless because they only show 'one side'. When have you ever seen a scatter plot like your one? It shows absolutely nothing and shows no relationship other than an unspecified amount of X salary earners have a car size of Y. Mine shows the breakdown.
A scatter plot is made to show relationships and how one variable affects another. Your scatter plot does not show this in the slightest.
Just because iTute says it doesnt meant it is right. Give it a few days and there will be a 'Thanks to John Smith for correctly pointing out that for Core, Question 10 is E'.