HL Maths May 2013 TZ2 discussion

Giveme45

In 15 mins were allowed to discuss :smile:

How did it go guys?

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Reply 1

ibmay2013

Section A of Paper 1 was fairly easy - the only question I can remember not doing well on is the geometric series one (I forgot the formula for a^3 - b^3). Also, I was uncertain about the question concerning arctan (it was something like arctan(blah) + arctan (blah) = arctan(1/p), find p).
For the last question in section B about complex numbers, the proof didn't work out for me (z1^n + z2^n = 2z3^n, or something like that).
Do you remember any other tough questions?

Reply 2

Giveme45

Original post by ibmay2013

The third degreee gemoetric sequence question admittedly was far too hard for a 6 marker. The trick was that you had to see that (r-1) was a obvious factor. So you would have (r-1)(quadratic). The coefficients of the quadratic are then found by identification. Then you had to solve the quadratic by using the discriminant, giving r=1, r=-1.67, r=2/3. the only possible answer was r=2/3 because it was an infinite sum.

The arctan question was solved by double angle formula of tan giving p=3, the following result was then pi/4.

The trick in the proof was to know that npi/3=5npi/3 (i think it was 3 not sure though), then the proof came flowing.

How did you do overall?

Reply 3

ibmay2013

Thanks for the explanations - I think both papers were of low to medium difficulty compared to past ones. There were quite a few calculus questions that gave a lot of marks and required little analytical thinking (simple differentiation, finding tangents etc.). Also, there seemed to be lots of easy giveaways (very simple four to five mark questions). So generally I feel pretty okay - you?

Reply 4

Giveme45

Original post by ibmay2013

I agree, the papers were very average compared to pastpapers, In the pastpapers I averaged about 110 marks, and in this one im expecting to get 113, you?

And yeah, a lot of easy giveaways, and most of the questions didnt require some 'sophisticated mathematical insight', I knew how to solve all of them, but due to silly mistakes i lost marks here and there.

Reply 5

ibmay2013

Wow, that's impressive - I usually scored around the high eighties to the low nineties, so I'm crossing my fingers for a 7. Hopefully I can boost my score through Paper 3.

Reply 6

Giveme45

Original post by ibmay2013

Wow, that's impressive - I usually scored around the high eighties to the low nineties, so I'm crossing my fingers for a 7. Hopefully I can boost my score through Paper 3.

Im sure you will! If my predictions hold true of what I currently will get (92 and 96% in both papers), then I only need 26% in paper 3 to get a 7, haha :biggrin:

Reply 7

DonBorat

youve just lowered my confidence

Reply 8

ibmay2013

For the last question of Section B Paper 2 (diagram of angle theta), I wrote theta = pi - arctan(8/x) - arctan(13/20-x) instead of 180. Will I miss the first few marks?

Reply 9

dylanmarks

Wow, you guys just destroyed the little hope I had in me! hahaha
I thought the papers were quite difficult... I mean, section A was fine, but section B destroyed me. :P

Reply 10

DonBorat

Original post by ibmay2013

For the last question of Section B Paper 2 (diagram of angle theta), I wrote theta = pi - arctan(8/x) - arctan(13/20-x) instead of 180. Will I miss the first few marks?

no its the same? or did it specify in angles

(edited 10 years ago)

Reply 11

DonBorat

Original post by dylanmarks

Wow, you guys just destroyed the little hope I had in me! hahaha
I thought the papers were quite difficult... I mean, section A was fine, but section B destroyed me. :P

tell me about it 113/120 :frown:

. How did everyone think this compared to may 2012 tz2?? I just wana know the relative boundaries

Reply 12

Giveme45

Original post by DonBorat

no its the same? or did it specify in angles

How would that make you lose anything...

Original post by DonBorat

tell me about it 113/120 :frown:

. How did everyone think this compared to may 2012 tz2?? I just wana know the relative boundaries

Haha you're also expecting to get 113/120? High five :biggrin:

Reply 13

ibmay2013

I think DonBorat is depressed about your prospects of getting 113/120. :P
I don't remember if they specified degrees vs radians, that's why I'm asking (plus they asked for particular values of theta given values of x, so my answers are different).

Reply 14

Giveme45

Original post by ibmay2013

Haha in paper 2 i had prospects about getting 120/120 but then i realised i made a stupid mistype mistake which will cost me atleast 1 mark for the expected income -.-

Dw if they dont specify, either are fine :smile:

Reply 15

DonBorat

Original post by Giveme45

how do you do that poison question? and what do you think a level 7 wouldbe

Reply 16

Giveme45

Original post by DonBorat

how do you do that poison question? and what do you think a level 7 wouldbe

The possible outcomes where

Saturday Sunday Income
3 0 120
0 3 120
2 1 180
1 2 180

You just calculated the combined probabilities of each of these outcomes, where X~Po(1.2), then divided them of the probability of having 3 requests in 3 days where X~Po(2.4), and multiplied them by the respective incomes. Adding these together gives 165$.

I think a 7 will be about 92.

Reply 17

DonBorat

Original post by Giveme45

haha i hope i get 1 mark atleast for writing X~p(2.4).

Reply 18

DonBorat

Original post by Giveme45

For the question |z1 + az2| was the answer root8

Reply 19

Examcram

Original post by dylanmarks

Wow, you guys just destroyed the little hope I had in me! hahaha
I thought the papers were quite difficult... I mean, section A was fine, but section B destroyed me. :P

I felt the same, although i didnt think the papers were quite difficult i thought they were VERY VERY difficult, i agree about section A being OK but section B was so hard...paper 1 not so much but section B paper 2 was so hard that instead of being calm and thinking clearly i went into total panic and completely flopped...to be honest its made me regret taking the IB but i shouldnt think that now since i still have 9 exams...reading how easy some people found it has also destroyed any hopes i had of low grade boundaries :/