***2015 LC Maths Paper 2 - Higher Level - June 8th***

simplyno1

skippy1977 wrote: »

Yep looks right. Method is good. The tangent doesn't have a x^2 though...(typo?)
x+3y-43=0 I think

Skippy can you tell me if my probability answer is right or wrong? I posted it up there

Dianabluex

prefer paper two happy

sdio

simplyno1 wrote: »

For the probability question where you had to prove P(n+1) = 0.6 + 0.2P(n),

i let n=1, and got P(2) = 0.6 + 0.2P(1). But P1= probabilty on first trial which was 0.7, therefore
P(2) = 0.6+(0.2)(0.7) = 0.74. So the probability of scoring on the 2nd throw is equal to 0.74.

I tested this: Probability of scoring on the 2nd throw is either 0.6, or 0.8, depends if he missed or scored. So I said the probability of scoring on the 2nd throw is (0.3x0.6) + (0.7 x 0.8) which equals to 0.74, therefore proving the equation...

is that right?

I think you need to prove it more generally.

P(n+1) = P(... S, S) + P(... U, S)
So P(n+1) = P(n)(0.8) + P(n-1)(0.6)

rooney1369

sdio wrote: »

I think you need to prove it more generally.

P(n+1) = P(... S, S) + P(... U, S)
So P(n+1) = P(n)(0.8) + P(n-1)(0.6)

Yep this is what I did . Couldn't get geometric part at all

dazzadazza

Am I the only one that feels that paper couldn't have gone any better?? Absolutely delighted!

tahtguy

Can someone please tell me what did the get for k in the co-ordinate geometry question.

skippy1977

tahtguy wrote: »

Can someone please tell me what did the get for k in the co-ordinate geometry question.

Just did it out and I got 3/4 and -48...would be fairly sure this is right.

Digitalmission

Thought that paper 2 was much easier than paper 1 overall

fin709

For the inferential statistics question part 2 did people use the z score formula to get 1.7 and then say thats less than 1.96 so we accept ho or did i do it wrong? some others did it different

Magnate

fin709 wrote: »

For the inferential statistics question part 2 did people use the z score formula to get 1.7 and then say thats less than 1.96 so we accept ho or did i do it wrong? some others did it different

Yep I think I did that, don't know if it's right or not.

skippy1977

simplyno1 wrote: »

Skippy can you tell me if my probability answer is right or wrong? I posted it up there

A quick look and I would have written that
P(n+1) = 0.8 P(n)+0.6(1-P(n))
P(n+1) = 0.8 P(n)+0.6-0.6 P(n)
P(n+1) = 0.6+0.2 P(n)

As someone mentioned they would be looking for a general solution that works in all cases....but I'd say some work with substitution would get marks too!

d (ii) is simply:

0.6+0.2 P(n)=P(n)
0.6=0.8 P(n)
P(n)=0.75
As P(n)=P
P=0.75

Hon the Dubs

fin709 wrote: »

For the inferential statistics question part 2 did people use the z score formula to get 1.7 and then say thats less than 1.96 so we accept ho or did i do it wrong? some others did it different

yep i did that but its 'fail to reject' not 'accept' right? Or maybe it doesn't matter

gryfothegreat

I loved it! It was definitely harder than P1 but somehow I think I did better... I got root365 for the radius. Only bits I couldn't attempt were 3 c and 8 d e f. Did ye all differentiate in Q9?

skippy1977

Magnate wrote: »

Yep I think I did that, don't know if it's right or not.

Yep that was it....test statistic was -1.71 which is in the 'fail to reject' region > that -1.96 and less than 1.96
1.71 gives the same answer.

Magnate

skippy1977 wrote: »

Yep that was it....test statistic was -1.71 which is in the 'fail to reject' region > that -1.96 and less than 1.96
1.71 gives the same answer.

Thank god, at least I know I did something right. Made a mess of that paper or at least it feels like it.

sdio

fin709 wrote: »

For the inferential statistics question part 2 did people use the z score formula to get 1.7 and then say thats less than 1.96 so we accept ho or did i do it wrong? some others did it different

I just saw that 94% was in the confidence interval from part 1.

Peg14

thought that was terrible but my other subjects I guess make up for it

Kremin

gryfothegreat wrote: »

I loved it! It was definitely harder than P1 but somehow I think I did better... I got root365 for the radius. Only bits I couldn't attempt were 3 c and 8 d e f. Did ye all differentiate in Q9?

hate to tell you but root365 is wrong. I made the same mistake... what we did was keep it as 4r instead of 3r when using pythag theorem. If we did it correctly, would have got r=20

Rimiko

skippy1977 wrote: »

Yep looks right. Method is good. The tangent doesn't have a x^2 though...(typo?)
x+3y-43=0 I think

Woops! That was a typo :P Yeah so with no x^2, great!

Kremin

Rimiko wrote: »

Woops! That was a typo :P Yeah so with no x^2, great!

Yeah thats what I got too..

What did everyone get for the distance from p to L1 when k is positive?


Anyway in my opinion- Q1 and Q2 were handy enough if you'd studied probability and inferential stats.

Q3 part C was rough, but the rest was fine.

Q4 Was simple enough.

Q5 was a really handy proof, same one on debs mock and the trig function was easy enough.

Q6 - Just a proof
q7- Got root365 for radius, now I know it was actually 20. I did everything else correctly from what I can see so hopefully only lose 3-5 marks for that mistake., it doesnt even hurt too many of the calculations because root365 isnt too much smaller than 20.
q8- that probability was hard. First few parts were okay once you realise what they want but the geometric series part was tough enough.

q9- I think this went okay, just cosine, sine and pythag theorem got h=10 in the end...

It appears they are really trying to push the fact they can mix paper 1 content with paper 2 content now?
E.g tan0 on paper 1 and now quadratic formulas + geometric sequences on paper 2??

I'm pretty confident I got an A1... as long as my mistakes are only small ones.

skippy1977

Kremin wrote: »

Yeah thats what I got too..

What did everyone get for the distance from p to L1 when k is positive?

3? I think

DarraghF197

Challenging paper, but did just as well in that as I did in Paper One

Finding k proved to be the the image of the plane question of Paper One. I got. 75 and 13.85. Took the right steps, but maximum one of those is right as the next bit said to use the one that is positive.

Spent a page doing the first part of the circle, why do they give us so little room?! I'm not fully sure if this is right, but it sounds sense: K (for centre) was (5,6)/(6,5).

Got to question 8/9 with an Applied Maths reminiscent question, and a brief unity between all Applied Maths students occurred! Albeit there wasn't much Applied Maths in it, but it definitely did help.

For those looking for the radius, I had 2/10 at the start. Then went back to check, and noticed that 20/73 squared would give you 20x73, not squaring the twenty. Found it at the very end and had to change everything. Not fully sure if my final area was right though. I got something like 15972.

MmmPancakes

skippy1977 wrote: »

3? I think

Yeah I got this too.

I'll share with you my not-so-finest moment, in the question with the velocity. I decided that solving quadratics the normal way wasn't for me, so I 'solved' (:o) it by taking out t as a factor and letting -6t + 22 = -8, got t = 5 instead of 4 and I only just realised how much of a muppet I am. How many marks should I lose, if my method for solving the angle was correct, but the value for OB was off?

Kremin

DarraghF197 wrote: »

Challenging paper, but did just as well in that as I did in Paper One

Finding k proved to be the the image of the plane question of Paper One. I got. 75 and 13.85. Took the right steps, but maximum one of those is right as the next bit said to use the one that is positive.

Spent a page doing the first part of the circle, why do they give us so little room?! I'm not fully sure if this is right, but it sounds sense: K (for centre) was (5,6)/(6,5).

Got to question 8/9 with an Applied Maths reminiscent question, and a brief unity between all Applied Maths students occurred! Albeit there wasn't much Applied Maths in it, but it definitely did help.

For those looking for the radius, I had 2/10 at the start. Then went back to check, and noticed that 20/73 squared would give you 20x73, not squaring the twenty. Found it at the very end and had to change everything. Not fully sure if my final area was right though. I got something like 15972.

I think 13.85 is around the right value for k, I got 13.8 or somewhere around there and got 7.5 for the distance... I did it a really long and confusing way though, so probably made a mistake lets be honest. Why is everyone saying the golf question was like an applied maths question? It wasn't a projectile question or anything, just trig?

Unless I completely missed something....

gryfothegreat

Kremin wrote: »

hate to tell you but root365 is wrong. I made the same mistake... what we did was keep it as 4r instead of 3r when using pythag theorem. If we did it correctly, would have got r=20

They'll still give us marks though, and they'll accept root365 for the rest of the problem I think? Oh well, I'm still happy with it!

Kremin

MmmPancakes wrote: »

Yeah I got this too.

I'll share with you my not-so-finest moment, in the question with the velocity. I decided that solving quadratics the normal way wasn't for me, so I 'solved' (:o) it by taking out t as a factor and letting -6t + 22 = -8, got t = 5 instead of 4 and I only just realised how much of a muppet I am. How many marks should I lose, if my method for solving the angle was correct, but the value for OB was off?

very few, maybe 2 or 3 for a basic numerical slip. Whatver you got for the angle will be marked correct if you use that value also, as you'll only be deducted marks once.

skippy1977

MmmPancakes wrote: »

Yeah I got this too.

I'll share with you my not-so-finest moment, in the question with the velocity. I decided that solving quadratics the normal way wasn't for me, so I 'solved' (:o) it by taking out t as a factor and letting -6t + 22 = -8, got t = 5 instead of 4 and I only just realised how much of a muppet I am. How many marks should I lose, if my method for solving the angle was correct, but the value for OB was off?

Ah we've all make those mistakes!! Ah if you're method was right you'll lose very little. You'll get 3/5 or 7/10 say and then they are meant to correct the rest based on your work.

Kremin

gryfothegreat wrote: »

They'll still give us marks though, and they'll accept root365 for the rest of the problem I think? Oh well, I'm still happy with it!

Oh yeah, its not like you'll get 0. You'll only be marked down once and if you continue and use the right steps you'll get the marks for using root 365

Barry1000

Completely wrong to try and integrate question 9 part a? haha

gryfothegreat

Kremin wrote: »

Oh yeah, its not like you'll get 0. You'll only be marked down once and if you continue and use the right steps you'll get the marks for using root 365

Yep that's what I mean!
Also, god bless that tan derivation...