***2015 LC Maths Paper 1 - Higher Level - June 5th***

Laurentf

Am I the only one who found it extremely tough? This is really worrying

tahtguy

Guys thats what I got for 8 (d). Can someone please tell me if my work makes any sense.

I got the volume of the oil slick when it reaches the land, The volume is: (100000)*pi*0.1

Then I let that equal to (4*10^6)t

t=250pi min
t=13 hrs and 5 mins

Unfortunately I left my answer as 250pi in the exam

Daire234

expiiplus1 wrote: »

I can't actually remember my precise number, but I recall noticing it was closer to 12 than I imagined. (I forgot cos could be negative) So yeah, that sounds about right.

Are you maybe getting mixed up with Q8 and Q9? There was no cosine function in q8, 'how long does it take for the oil to reach the shore' was the question I was referring to.

Daire234

tahtguy wrote: »

Guys thats what I got for 8 (d). Can someone please tell me if my work makes any sense.

I got the volume of the oil slick when it reaches the land, The volume is: (100000)*pi*0.1

Then I let that equal to (4*10^6)t

t=250pi min
t=13 hrs and 5 mins

Unfortunately I left my answer as 250pi in the exam

Yes I got the same answer

tahtguy

Daire234 wrote: »

Yes I got the same answer

do u think I will lose much marks for leaving it as 250pi?

Peregrine

tahtguy wrote: »

do u think I will lose much marks for leaving it as 250pi?

No, you should get most of the marks.

Daire234

tahtguy wrote: »

do u think I will lose much marks for leaving it as 250pi?

I think it will be marked hard because it wasn't a difficult paper, at most 3 marks, all you forgot to do was divide by 60

darrenid

in one of the last few questions were you supposed to put your calculator in radian mode?

expiiplus1

Daire234 wrote: »

Are you maybe getting mixed up with Q8 and Q9? There was no cosine function in q8, 'how long does it take for the oil to reach the shore' was the question I was referring to.

Yes, that was it. Sorry I can't remember what I got for that at all. I just remember that you calculated the time when the radius of the circle was 1km. It was a straightforward enough problem, once you got that trick, so apart from messing up with the units (which at first I did - more reason to loathe Project Maths) there wasn't much you could do wrong

expiiplus1

Laurentf wrote: »

Am I the only one who found it extremely tough? This is really worrying

I wouldn't be worried. You have a bit of a bias here, as only the people who did really well - or felt they did - are going to post about it.

Do You Even Squat

What did everyone get for the last part of q9?

d1234

Laurentf wrote: »

Am I the only one who found it extremely tough? This is really worrying

I found it really tough too!! Think I passed - hoping for a C2 but not sure at this stage whether I'll get it or not

d1234

Found the answers done out on line - https://cdn.shopify.com/s/files/1/0371/6905/files/LCHM_P1_ANSWERS_15.Image.Marked.pdf?15485021131360528641 - marking scheme will be released in August

Daire234

Do You Even Squat wrote: »

What did everyone get for the last part of q9?

I think it was 12.224 hrs

Broseph

Daire234 wrote: »

I think it was 12.224 hrs

Got 10 hours 45 but in the exam I got 13 I think, because integrating sin is -cos I left it as positive

rwalsh97

These worked solutions are incorrect in many places. Q1, he doesn't account for the ball being dropped from a height of 2 metres, instead he assumes it is first thrown to that height.
Other various questions there are errors such as not squaring the value for r in pir^2 etc.
By the way, answer to the last question, part d of q9 was 15 hours 15 minutes. 12 hours is incorrect as that's the length of the shortest day (roughly), and we know the longest day is 17, or 17h15 which I got... so I can confidently say after minutes of scribbles and starting again on the back of the exam, my final answer cas correct.
source: lc hl 2015 student

Do You Even Squat

Broseph wrote: »

Got 10 hours 45 but in the exam I got 13 I think, because integrating sin is -cos I left it as positive

Got 10 hours 45 as well

Broseph

Do You Even Squat wrote: »

Got 10 hours 45 as well

For the average day length?

Do You Even Squat

Broseph wrote: »

For the average day length?

yes

Broseph

Do You Even Squat wrote: »

yes

For the complex numbers question I did it twice and got 0 and -1/w it depends if u look at it like w^n-1 is the nth term because of the 1 at the beginning or look at it as the n-1th term including the 1 I. I did it as a sequence leaving out the one altogether and saying the first term was w and then got zero a second time but I think -1/w is correct because they said 'in its simplest terms' that's probably not 0

rwalsh97

Broseph wrote: »

For the complex numbers question I did it twice and got 0 and -1/w it depends if u look at it like w^n-1 is the nth term because of the 1 at the beginning or look at it as the n-1th term including the 1 I. I did it as a sequence leaving out the one altogether and saying the first term was w and then got zero a second time but I think -1/w is correct because they said 'in its simplest terms' that's probably not 0

I got 0 too, the other A1 guy in my class got 0, I think it's 0, or 0 + 0i, which i didnt write it as anyway

Do You Even Squat

Broseph wrote: »

For the complex numbers question I did it twice and got 0 and -1/w it depends if u look at it like w^n-1 is the nth term because of the 1 at the beginning or look at it as the n-1th term including the 1 I. I did it as a sequence leaving out the one altogether and saying the first term was w and then got zero a second time but I think -1/w is correct because they said 'in its simplest terms' that's probably not 0

I did it twice and got 3 different answers: 0, -1/w and i cant remember the other. Hopefully i get some attempt marks

Broseph

Do You Even Squat wrote: »

I did it twice and got 3 different answers: 0, -1/w and i cant remember the other. Hopefully i get some attempt marks

At least 7/10 Id say

Peregrine

tahtguy wrote: »

Guys thats what I got for 8 (d). Can someone please tell me if my work makes any sense.

I got the volume of the oil slick when it reaches the land, The volume is: (100000)*pi*0.1

Then I let that equal to (4*10^6)t

t=250pi min
t=13 hrs and 5 mins

Unfortunately I left my answer as 250pi in the exam

The expression for volume is incorrect, the radius should be squared but as far as I can tell, your final answer is correct. I presume you just forget to type out the square?

expiiplus1

rwalsh97 wrote: »

These worked solutions are incorrect in many places. Q1, he doesn't account for the ball being dropped from a height of 2 metres, instead he assumes it is first thrown to that height.
Other various questions there are errors such as not squaring the value for r in pir^2 etc.
By the way, answer to the last question, part d of q9 was 15 hours 15 minutes. 12 hours is incorrect as that's the length of the shortest day (roughly), and we know the longest day is 17, or 17h15 which I got... so I can confidently say after minutes of scribbles and starting again on the back of the exam, my final answer cas correct.
source: lc hl 2015 student

Sorry, you're the one who is wrong. sin can be negative and so days can be less than 12.25 hours.

expiiplus1

Also 0 is definitely the right answer to the complex number problem. They adapted a well known problem. Google "roots of unity"

Kremin

expiiplus1 wrote: »

Also 0 is definitely the right answer to the complex number problem. They adapted a well known problem. Google "roots of unity"

Are people still debating this? I posted a proof why theres n terms if you include 1 and n-1 if you just start the sequence from w...

Daire234

Broseph wrote: »

Got 10 hours 45 but in the exam I got 13 I think, because integrating sin is -cos I left it as positive

when you were integrating I think you divided by pi/365, which is incorrect as pi does not equal 3.14 in this case, you were supposed to divide by 72/73

Broseph

Daire234 wrote: »

when you were integrating I think you divided by pi/365, which is incorrect as pi does not equal 3.14 in this case, you were supposed to divide by 72/73

Why? I was using radian mode

fin709

For question 1 part 2 do you not just add 2, 3/2, 3/2 and so on... why has the solution guy done it different?

Kremin

Daire234 wrote: »

when you were integrating I think you divided by pi/365, which is incorrect as pi does not equal 3.14 in this case, you were supposed to divide by 72/73

The question said (in radians) so changing the mode of your calculator to Radians would have saved a whole lot of confusion and time guys .
I made the exact same mistake honestly, did everything in degrees, was really confused how my avg # of hours was lower than the shortest day, then it clicked that I had done everything in degrees whilst using the pi symbol which is 3.14 in deg, not 180....

Daire234

Broseph wrote: »

Why? I was using radian mode

I could be wrong, but I think radian mode only works when you are using a trigonometric function, when you brought pi outside it changes to 3.14 even if it is in radian mode and it should equal 180

j9876

Looked over the paper there and kicking myself.... I never multiplied out my complex no. answer so it is left as a fraction and forgot to round off my financial maths question. Will I lose many marks do you think?

Broseph

Daire234 wrote: »

I could be wrong, but I think radian mode only works when you are using a trigonometric function, when you brought pi outside it changes to 3.14 even if it is in radian mode and it should equal 180

But even if the angle is in radians it doesn't matter if you bring the pi outside and multiply by it because you're not multiplying by pi the angle your multiplying by pi the number. I see what youean though I don't know if the pi keeps the 180 value when you bring it outside the trigonometric function or does is change to 3.14?

Kremin

j9876 wrote: »

Looked over the paper there and kicking myself.... I never multiplied out my complex no. answer so it is left as a fraction and forgot to round off my financial maths question. Will I lose many marks do you think?

Only if theyre really desperate to take marks away, but you did finish the sums, and correctly i assume, so small things like forgetting to simplify fully should only be max 2 marks lost.

expiiplus1

Kremin wrote: »

Only if theyre really desperate to take marks away, but you did finish the sums, and correctly i assume, so small things like forgetting to simplify fully should only be max 2 marks lost.

Thanks Kremin.
Many people don't seem to realise what a mathematical proof is. We're not talking about English - something's either right or wrong.

dazzadazza

Kremin wrote: »

Only if theyre really desperate to take marks away, but you did finish the sums, and correctly i assume, so small things like forgetting to simplify fully should only be max 2 marks lost.

Sorry just wondering Kremin are you a teacher or a student? Haha

muller55

Anyone got the solutions to Q7 and Q9?

Kremin

dazzadazza wrote: »

Sorry just wondering Kremin are you a teacher or a student? Haha

A student, ha.

theRB

expiiplus1 wrote: »

Sorry, you're the one who is wrong. sin can be negative and so days can be less than 12.25 hours.

If you just think about it, if the day length is 12.25hrs on March 21, as they get longer over the summer the average length will obviously be more than 12.25hrs. I got 15hrs15mins which I'm happy with.

dazzadazza

Kremin wrote: »

A student, ha.

You seem to know what you're talking about lol... Are you looking for an A1 in this?

Kremin

dazzadazza wrote: »

You seem to know what you're talking about lol... Are you looking for an A1 in this?

Well, I've been lurking these threads since they were created so at this point, just reciting what other people have said and what my teachers have told me. And yeah I'm aiming for an A1 Maths is by far my favourite subject in school

fin709 wrote: »

For question 1 part 2 do you not just add 2, 3/2, 3/2 and so on... why has the solution guy done it different?

Which solution guy are you referring to?

j9876

Do you guys think that the exam will be marked extra hard this year due to the majority of students saying it was easy?

DarraghF197

j9876 wrote: »

Do you guys think that the exam will be marked extra hard this year due to the majority of students saying it was easy?

Looks like it. One way or the other, it has to fit the bell curve. They're probably not able to give one question 35 marks and the other 15. But for the complex numbers, for example, a lot more marks might be for the second part to as that was probably answered worse than the first.

Sxcshoes

They'll take the sample first and decide on the majority of marks then. I don't think the media will influence the marking scheme. I don't think I did well in that exam but sadly it's not so much about my ability it's more about how other people fair against me. A competition more than an exam.

tornados2111

Sxcshoes wrote: »

They'll take the sample first and decide on the majority of marks then. I don't think the media will influence the marking scheme. I don't think I did well in that exam but sadly it's not so much about my ability it's more about how other people fair against me. A competition more than an exam.

Will they use a sample proportion and use a 95% confidence interval? Or will they get the mean mark and standard deviation and test their hypothesis?

fin709

Kremin wrote: »

Well, I've been lurking these threads since they were created so at this point, just reciting what other people have said and what my teachers have told me. And yeah I'm aiming for an A1 Maths is by far my favourite subject in school



Which solution guy are you referring to?

The solutions that were posted a few pages back

Yoyoyobobobo

Does anyone have the solutions to questions 7-9? I know someone posted it a few pages back but I couldn't open the link without having to sign up to some page! Thanks

Kremin

fin709 wrote: »

The solutions that were posted a few pages back

Well I don't know the particular ones but you could do the question two ways:

A geometric series for n=4 or just do it manually..
The reason you add 3/2 twice and all the other bounces twice is because the ball goes up and down the same distance.

expiiplus1

theRB wrote: »

If you just think about it, if the day length is 12.25hrs on March 21, as they get longer over the summer the average length will obviously be more than 12.25hrs. I got 15hrs15mins which I'm happy with.

That might be true (I can't actually recall what I got), but the fact is that 12.25 is NOT the lowest value all year eg. March 20 is shorter.