**HL Maths P2 Before/After

cocopopsxx

How did everyone go about doing the probability long question?

DepoProvera

patrickkelly wrote: »

Anybody get Alpha= 44Degreees and Beta=100Degrees for part (i) of question 8?

I got this also.. Quite complicated.. Used cosine rule twice and ended up having to add to angles to get alpha

Hayezer

SOUND FOR THAT ROBOT ARM ANYWAY SEC

patrickkelly

DepoProvera wrote: »

I got this also.. Quite complicated.. Used cosine rule twice and ended up having to add to angles to get alpha

Ya i was the same! ended up getting beta to be most effected by the 1% error by using circles, and found that when beta is greater the 90degrees, that the 1% effects beta more, but when beta was less then 90 degrees, the 1%effects alpha more, all by use of circles and displacement along an arc!
Any body agree?

DepoProvera

For the error of 1 degree question.. Did anyone else end up drawing arcs from P and Q to R and using l=rxtheta with each angle and then 1+ each angle, then subtracting to see which is greater distance?

DepoProvera

patrickkelly wrote: »

Ya i was the same! ended up getting beta to be most effected by the 1% error by using circles, and found that when beta is greater the 90degrees, that the 1% effects beta more, but when beta was less then 90 degrees, the 1%effects alpha more, all by use of circles and displacement along an arc!
Any body agree?

Woop same man!

patrickkelly

DepoProvera wrote: »

Woop same man!

And for the final part? Did u draw a circle radius 12 from centre Q, and then draw a line PQ, where this line intersected the circle, from the point 0,0 drew 2 semi circles from these points to the x-axis, and shaded the region between them?

DepoProvera

cocopopsxx wrote: »

How did everyone go about doing the probability long question?

I got .31 for the first part.. For 2nd and 3rd I originally thought it was conditional prob but it wasn't? 2nd was straightforward and 3rd I subtracted those who were neither Arrear or Negative Equity and then subtracted those who were negative eq from that value to find total arrear(12 thousand something) my answer for part 3 was like .9 something!

clairekitteh

patrickkelly wrote: »

Anybody get Alpha= 44Degreees and Beta=100Degrees for part (i) of question 8?

Yes I got that...

What did everyone do for the very last part of the last Q?

WestIRL

Again. Anyone get root2 as K for Q3? I know my method's right but I'm pretty sure my actual answer is wrong.

WestIRL

clairekitteh wrote: »

Yes I got that...

What did everyone do for the very last part of the last Q?

About 2min left and just filled in points on the graph where I though R would lie. Terribly measured but a few attempt marks.

DepoProvera

patrickkelly wrote: »

And for the final part? Did u draw a circle radius 12 from centre Q, and then draw a line PQ, where this line intersected the circle, from the point 0,0 drew 2 semi circles from these points to the x-axis, and shaded the region between them?

Centre P you mean? I drew an arc of 12 around then a smaller arc for the Q.. It have me a sort of rainbow and I shaded in the inside.. However it's just dawned on me that it should have gone below the x axis aswell damnnit!

MattHelders

DepoProvera wrote: »

Centre P you mean? I drew an arc of 12 around then a smaller arc for the Q.. It have me a sort of rainbow and I shaded in the inside.. However it's just dawned on me that it should have gone below the x axis aswell damnnit!

I got some crazy shape. 5 minuted left I realised it would cross the x axis. Got it done in the end so hoping for at least a decent chunk of the marks

patrickkelly

DepoProvera wrote: »

Centre P you mean? I drew an arc of 12 around then a smaller arc for the Q.. It have me a sort of rainbow and I shaded in the inside.. However it's just dawned on me that it should have gone below the x axis aswell damnnit!

ya i cant remember the points now exactly but i got that rainbow shape aswell!
In regards the x-axis, your told Alpha has a maximum of 180degrees, as does beta, so therefore it will never go bellow the x-axis?

or am I incorrect?

DepoProvera

What did everyone get for the % increase of rejected batteries? I am never sure if percent increase is a figure like 120% .. mine was 27% increase or something close to that

MattHelders

DepoProvera wrote: »

What did everyone get for the % increase of rejected batteries? I am never sure if percent increase is a figure like 120% .. mine was 27% increase or something close to that

I got 29 but I got the part (i) wrong

patrickkelly

patrickkelly wrote: »

ya i cant remember the points now exactly but i got that rainbow shape aswell!
In regards the x-axis, your told Alpha has a maximum of 180degrees, as does beta, so therefore it will never go bellow the x-axis?

or am I incorrect?

Just realised my mistake now, 2 semi circles of radius 12 should be drawn drom where the point Q hits the x-axis, going bellow the x-axis

mathstalk

My answers (The Ones I remember)

1) Yes, it's a parallelogram, found midpoint between AD and BC and they were the same.

2) K is something like 2+root(2) or 1+root(2), can't remember. I solved it using geometry and trigonometry

3) Alpha is 45" and Beta is 80", I think. Oh and I use the "Store as letters" function on my SHARP El-W531, so that figure is either exactly accurate or wrong.

4) The last question, I think it ends up as a half-donut shape, looking like it has a piece bitten off it and a round end at one side. Hard to explain.

5) The percentage change in the "rejected coins" rate, I got to be something like 94%. That is, the 1% increased to something like 2%, hence the "rate" itself went up by 94%.

That's all I can remember for now. Maybe I'll post again later.

DepoProvera

patrickkelly wrote: »

ya i cant remember the points now exactly but i got that rainbow shape aswell!
In regards the x-axis, your told Alpha has a maximum of 180degrees, as does beta, so therefore it will never go bellow the x-axis?

or am I incorrect?

That's what I thought in the exam but if alpha is 0 or 180 then beta could extend the arm below the x axis? I hope we are right anyway!

MattHelders

patrickkelly wrote: »

Just realised my mistake now, 2 semi circles of radius 12 should be drawn drom where the point Q hits the x-axis, going bellow the x-axis

But surely if alpha was 0 degrees and beta was 90 degrees it would go below?

c28omzk7ihsxv0

DepoProvera wrote: »

For the error of 1 degree question.. Did anyone else end up drawing arcs from P and Q to R and using l=rxtheta with each angle and then 1+ each angle, then subtracting to see which is greater distance?

I did the same, seemed right.

Also for alpha and Beta I got 44. something and seventy something.

patrickkelly

DepoProvera wrote: »

That's what I thought in the exam but if alpha is 0 or 180 then beta could extend the arm below the x axis? I hope we are right anyway!

Ya i see that now! and there is a semi circle missing aswell at the right hand side of (0.0)! and under that there is another semi circle

DepoProvera

Hadlee Old-fashioned Archer wrote: »

I did the same, seemed right.

Also for alpha and Beta I got 44. something and 100. something.
It said correct to one decimal place didn't it?

It didn't ask for any figures specifically I think ? Or do you mean the angles because they were to the nearest degree(I got those angles aswell)

TheBody

Could somebody post a scanned copy of the exam please (assuming you are exempt from Irish paper 1 of course!!).

DepoProvera

patrickkelly wrote: »

Ya i see that now! and there is a semi circle missing aswell at the right hand side of (0.0)! and under that there is another semi circle

Ah well I'd say we'll get a good chunk of the marks there though! :P

patrickkelly

mathstalk wrote: »

My answers (The Ones I remember)

1) Yes, it's a parallelogram, found midpoint between AD and BC and they were the same.

2) K is something like 2+root(2) or 1+root(2), can't remember. I solved it using geometry and trigonometry

3) Alpha is 45" and Beta is 80", I think. Oh and I use the "Store as letters" function on my SHARP El-W531, so that figure is either exactly accurate or wrong.

4) The last question, I think it ends up as a half-donut shape, looking like it has a piece bitten off it and a round end at one side. Hard to explain.


5) The percentage change in the "rejected coins" rate, I got to be something like 94%. That is, the 1% increased to something like 2%, hence the "rate" itself went up by 94%.

Got mostly the same as these with exception to the drawing of that doughnut shaped graph, I can see where i went wrong on it though!


the " circles which had a common point (4,7), question 5 >I THINK< did anybody get x+2y=18 for the equation of this line?

DepoProvera

patrickkelly wrote: »

Got mostly the same as these with exception to the drawing of that doughnut shaped graph, I can see where i went wrong on it though!


the " circles which had a common point (4,7), question 5 >I THINK< did anybody get x+2y=18 for the equation of this line?

Yeah I think I got that..just got slope between centres, common chord was perpindicular then just used y-y1 formula

patrickkelly

DepoProvera wrote: »

Yeah I think I got that..just got slope between centres, common chord was perpindicular then just used y-y1 formula

Ya spot on, did u just draw it to prove that thet were touching?

QueenOfLeon

TheBody wrote: »

Could somebody post a scanned copy of the exam please (assuming you are exempt from Irish paper 1 of course!!).

The paper should be up on examinations.ie fairly soon.

DepoProvera

patrickkelly wrote: »

Ya spot on, did u just draw it to prove that thet were touching?

Nah I just got distance between centres and radii of both circles.. Subtracted or added can't remember but it worked out