**HL Maths P2 Before/After

Tankosaur

jackindebox94 wrote: »

if you are saying beta is 80 you left out a minus sign when working out the angle. apologies for having to tell you that. k=3 because 1,1 and k,k were on the circle with centre of (k+1)/2,(k+1)/2. look i guess we'll see when the marking scheme comes out.

I guessed k=2 and it worked out for every single equation possible so I'm just hoping k=2 is right.....

jackindebox94

DepoProvera wrote: »

jackindebox94 wrote: »

if Im wrong Im really sorry but the question says if you pick from all those in arrears what is the probability that they will be both in arrears and negative equity but the thing is there are only 723 people who are in negative equity

"Of the 475 136 properties examined, 145 414 of them were in negative equity"

ya but you have to find out how many people are in both negative equity and arrears and that is equal to 474316-145414-11644-317355(no of people in neither) = 723.

jackindebox94

DepoProvera wrote: »

jackindebox94 wrote: »

if Im wrong Im really sorry but the question says if you pick from all those in arrears what is the probability that they will be both in arrears and negative equity but the thing is there are only 723 people who are in negative equity

"Of the 475 136 properties examined, 145 414 of them were in negative equity"

ya but you have to find out how many people are in both negative equity and arrears and that is equal to 474316-145414-11644-317355(no of people in neither) = 723.

Tankosaur

jackindebox94 wrote: »

ya but you have to find out how many people are in both negative equity and arrears and that is equal to 474316-145414-11644-317355(no of people in neither) = 723.

Sadly my good man that is wrong.


The number of people in arrears and negative equity is contained the the number of people in negative equity.

So by taking away 145414 and 11644 you are taking 11644 away twice.


the qeustion states : 145414 were in negative equity, of these 11644 were in arrears.

ImFudged

leaveiton wrote: »

I don't have a background in physics/DCG/applied maths that would have helped me out.

Yeah DCG and Physics really helped me in this paper. I kept thinking of Resultant vectors :]

sdiff

jackindebox94 wrote: »

if you are saying beta is 80 you left out a minus sign when working out the angle. apologies for having to tell you that. k=3 because 1,1 and k,k were on the circle with centre of (k+1)/2,(k+1)/2. look i guess we'll see when the marking scheme comes out.

How did you get k=3

DepoProvera

Tankosaur wrote: »

Nope, there were 3 values, 1 the total,2 the people not in arrears or negative equity,3 the people in negative ( and the people ( out of these) who are in negative equity.)


so take 2 and 3 from 1 to give you the people in arrears and postive equity.


add this to those in negative equity and arrears to get the total in arrears then divide the number in negative eq and arrears by this total.

answer came to about 47%

Those in total in arrears is total - those in neither NE or A - those in NE which gives 12367...? Ah **** it post mortems are a bad idea I did much worse than I initially thought.. Bye A1/2

jackindebox94

Tankosaur wrote: »

jackindebox94 wrote: »

ya but you have to find out how many people are in both negative equity and arrears and that is equal to 474316-145414-11644-317355(no of people in neither) = 723.

Sadly my good man that is wrong.


The number of people in arrears and negative equity is contained the the number of people in negative equity.

So by taking away 145414 and 11644 you are taking 11644 away twice.


the qeustion states : 145414 were in negative equity, of these 11644 were in arrears.

yes you are spot on ive been arguing a point having read the question wrong. thanks for making me aware of that!!

Tankosaur

DepoProvera wrote: »

Those in total in arrears is total - those in neither NE or A - those in NE which gives 12367...? Ah **** it post mortems are a bad idea I did much worse than I initially thought.. Bye A1/2

you'll lose maybe 3 marks at best.

Akanthia

Did anyone notice a serious disconnect between sample papers given and the one we receieved? i thoght the circle question was unreasonable in the time given and after i read the papagraph on arrears and the questions i cried. i lef question 7 and 8 almost blank loosing 150 marks and the A i was hoping for {and got in the mocks}. so because of project maths and the time i spent learing it over my other subjectsim gonna loose a year of my life.


SEC- paper 2 was chernobyl.

when i repeat and make money i will duely sue you:D:D:D:D

RedTexan

What did ye say for the position where a change in alpha results in a greater change in the position of R than a change in beta and vice versa? Was it when the distance between P and R is greater than 12 (QR) and therefore making and arc with a larger radius? And I think K=5.828, seems to be a common solution

DepoProvera

Tankosaur wrote: »

you'll lose maybe 3 marks at best.

Well done for keeping your head and spotting that during the exam! You'd be good at the HPAT

sdiff

RedTexan wrote: »

What did ye say for the position where a change in alpha results in a greater change in the position of R than a change in beta and vice versa? Was it when the distance between P and R is greater than 12 (QR) and therefore making and arc with a larger radius? And I think K=5.828, seems to be a common solution

well arc length = radius by change in angle... since change in angle is one, the only relevant figure is radius. The corresponding radius for alpha was larger.

Wanchor

I left k = x. Did it ask for any format, specifically an integer/float?

Feel_The_Byrne

What does 'direction of casuality' actually mean? Plus I got k=3, but I think the answer is actually k=6. If you measured from the origin to where the first tangent crossed the x axis, you could use this distance to mark the x axis and easily figure out k. I did it in 30 seconds although I used 1 , as my first point when it should've been 2 so I'll lose 3 marks at most. I loved this test overall though !

sdiff

Feel_The_Byrne wrote: »

What does 'direction of casuality' actually mean? Plus I got k=3, but I think the answer is actually k=6. If you measured from the origin to where the first tangent crossed the x axis, you could use this distance to mark the x axis and easily figure out k. I did it in 30 seconds although I used 1 , as my first point when it should've been 2 so I'll lose 3 marks at most. I loved this test overall though !

Using perpendicular distance formulae for the tangents I got 5.8. The distance from the centre to each of the tangents is the same, namely the radius. Centre = (r,r) where r is the radius.

Direction of causality is which variable causes which, i.e in this case it could have been arrears causing interest, or interest causing arrears (or no causality).

gethepoints

Akanthia wrote: »

Did anyone notice a serious disconnect between sample papers given and the one we receieved? i thoght the circle question was unreasonable in the time given and after i read the papagraph on arrears and the questions i cried. i lef question 7 and 8 almost blank loosing 150 marks and the A i was hoping for {and got in the mocks}. so because of project maths and the time i spent learing it over my other subjectsim gonna loose a year of my life.


SEC- paper 2 was chernobyl.

when i repeat and make money i will duely sue you:D:D:D:D

Hi5! Exact same thought here. I practised all the Folen sample papers and none of the frikin trig identities came up. I was hoping for a guaranteed 25 marks on Q5 but nooooo.. SEC decided to mix it up a bit and switch it to probabilities. Also, 2 years of maths and a frikin parallelogram??? Total bullsh!t.

I calculated and.. 50% on paper 1 and 30% on this paper rounds up to a total of 40% on the spot. If i get any lower, I'll pray to God that the one correcting my exam rounds it to a pass.:mad::mad::mad::mad::mad:

Feel_The_Byrne

sdiff wrote: »

Using perpendicular distance formulae for the tangents I got 5.8. The distance from the centre to each of the tangents is the same, namely the radius. Centre = (r,r) where r is the radius.

Direction of causality is which variable causes which, i.e in this case it could have been arrears causing interest, or interest causing arrears (or no causality).

Thanks, you may be right but this is the answer that's going around my school.

Hmmm I think I said something like that, hopefully I get some attempt marks.

Did anyone actually cover this in their school though, I never saw this term before (I saw casuality but not direction of casuality)

Tankosaur

DepoProvera wrote: »

Well done for keeping your head and spotting that during the exam! You'd be good at the HPAT

I got 199 in my hpat.

sdiff

Feel_The_Byrne wrote: »

Thanks, you may be right but this is the answer that's going around my school.

Hmmm I think I said something like that, hopefully I get some attempt marks.

Did anyone actually cover this in their school though, I never saw this term before (I saw casuality but not direction of casuality)

Never went over it, but I figured out that that made the most sense. My first instinct was "positive correlation" - but that doesn't make sense because the questions states that it is important to note... whereas positive correlation is just common sense.

RedTexan

sdiff wrote: »

Using perpendicular distance formulae for the tangents I got 5.8. The distance from the centre to each of the tangents is the same, namely the radius. Centre = (r,r) where r is the radius.

Direction of causality is which variable causes which, i.e in this case it could have been arrears causing interest, or interest causing arrears (or no causality).

I just spoke about causality saying an increase in interest rates had a causal relationship with the arrears, was this basically it?

sdiff

RedTexan wrote: »

I just spoke about causality saying an increase in interest rates had a causal relationship with the arrears, was this basically it?

Well that might not be the case. Which "direction" is the causality in - i.e, are high interest rates causing higher arrears rates? Or are higher arrears rates causing higher interest rates? Tbh though I think they will be very lenient for this Q.

BL1993

The value of k for q3 is definitely 5.83

RedTexan

sdiff wrote: »

Well that might not be the case. Which "direction" is the causality in - i.e, are high interest rates causing higher arrears rates? Or are higher arrears rates causing higher interest rates? Tbh though I think they will be very lenient for this Q.

That's a question for an economist, not a leaving cert maths exam. I'd hope going on about how high interest rates were corresponding with the high % of arrears would get me there. There were some terribly worded question ie. thh percentage increase? I said 94% but it would appear I was wrong, still should get the majority of marks there though for showing the amount of batteries and that

Dapics

RedTexan wrote: »

That's a question for an economist, not a leaving cert maths exam. I'd hope going on about how high interest rates were corresponding with the high % of arrears would get me there. There were some terribly worded question ie. thh percentage increase? I said 94% but it would appear I was wrong, still should get the majority of marks there though for showing the amount of batteries and that

Causility does not imply correalation....

The shape of the data is in such a direction.
In 2009, there was no correlation, also there was no causility.

in 2011, there was a positive LINEAR relationship between interest rates and precentage of population.

Causility implies there has been an increase in the amount of people in arrears AND the increase in interest rates as a subsequent result.

The emphasis is that as interest rates increased, it was harder for people to repay mortgage, therefore amount of people unable to pay mortgage increased from 2009-2011.

The direction of the causility is the outward movement of the linear relationship.

Thats the way I argued it.

RedTexan

I said about that it may indeed not imply causality and continued to say they strong positive correlation between the two would suggest that as the interest increases an increase in the size of arrears is noted. Had ye actually specifically covered 'direction of causality', I think it specified to September 2011 too in the question btw

RedTexan

And for the hypothesis test does it matter which one you state as the null hypothesis and which you state as the alternative?

Dapics

RedTexan wrote: »

And for the hypothesis test does it matter which one you state as the null hypothesis and which you state as the alternative?

no as long as you stated that value is not within set of values therfore hypothesis is false ,

H0 =PROB FALSE
H1 =PROB TRUE



you should then have linked result to H0, therefore hypothesis is false that value is within set of data

RedTexan

Dapics wrote: »

no as long as you stated that value is not within set of values therfore hypothesis is false ,

H0 =PROB FALSE
H1 =PROB TRUE



you should then have linked result to H0, therefore hypothesis is false that value is within set of data

Yeah I had H0-that it was .31 I think and then rejected this with my confidence interval all's well that ends well!

Dapics

RedTexan wrote: »

I said about that it may indeed not imply causality and continued to say they strong positive correlation between the two would suggest that as the interest increases an increase in the size of arrears is noted. Had ye actually specifically covered 'direction of causality', I think it specified to September 2011 too in the question btw

we hadn't covered it but i knew what causility meant. i heard it on a program on youtube regarding some complex statistics

they should be generous in marks for it