Paper 42 (13th May) - Full Solutions

[Ebby_SaLeem]

Finally got access to the paper and I would like to thank you a lot sir for this! I wanted to ask you these questions:
If we calculate minor arc how many marks will I lose? i remember my answer was 19 something...
For the probability thing, probability of wearing gloves was 7/10 so not wearing gloves will be 3/10... so i did P(no hat, no scarf, no gloves) = 5/8 * 5/6 * 3/10 isn't this correct? :/
for the speed of water i got 1.74 cm/min and not 1740 how many marks will be deducted?
for finding OP3 i used similarity and pythagoras theorem but my answer was 2.07 something
and lol i had no clue at all for calculating n i just wrote crazy numbers!
Thanks a lot sir!

 

[notnek01]

For the question with the hexagon: the b part I forgot to change litres into cm3 and instead I carried on the working with 12 and not 12000, will I get marks for my working?

If you followed the rest of the method correctly I'll guess you'll get 2 marks.

 

[Ebby_SaLeem]

shit!
i will get 124 out of 130
and in paper 2 will get 69 out of 70
i hope im right.
so did i get a world ranking? xD

congrats larkay!

 

[uzair shahid]

in question 4d) if i multiply by 2 how much will i get?

 

[uzair shahid]

in question 3d) if we write the coordinates 2.6,3.1
will i get the marks?

 

[notnek01]

For the question with the hexagon: the b part I forgot to change litres into cm3 and instead I carried on the working with 12 and not 12000, will I get marks for my working?

If you followed the rest of the method correctly I'll guess you'll get 2 marks.

 

[notnek01]

Another question, for the water flow question, how many marks would I get if I put 1744? (Instead of 1740)

You may lose a mark, I'm not sure.

 

[Princess Raven]

its not opening..

 

[notnek01]

Hey Sir...First of all you've done a very good job
I have some questions....
In Probability Q8-(b)(iii)
I calculated 1-(wearing both).... Is that right? The question didn't mention excluding "not wearing both hat and scarf"...
So i wrote 1-((5/8)*(2/3))= 7/12

Secondly....In Question 11(c)
I didn't understand what u did there... but i got the same answer (3.7) by using similar triangle with each other till I get OP5 at the end...
Can u explain to me what did u do exactly?
Thanks in Advance...

8biii) The question asks for 'wears a hat or a scarf' but 'not wearing both hat and scarf' doesn't include a hat or a scarf so this is not part of the probability. You may get no marks here and possibly 1.

11c. I did the same as you but using a shortcut method. The scale factor is the same each time (sqrt(10)/3).

 

[M.A.H]

24 hours have passed so here are full solutions to the 13th May IGCSE Maths Paper 42. These are my (IGCSE maths teacher) solutions and not the official solutions from CIE.

I’ll try to answer any questions regarding this paper but...

Since I don’t want to make any predictions that could be wrong, I will not answer any questions like, 'What will I need to get this grade?' or 'How hard/easy was the paper, what will the A boundary be?'.

I’ll only say that I thought it was a very hard paper, one of the hardest in recent years.

Here are the average total grade boundaries over the last 2 years:

A* : 174.7/200
A : 145.6/200
B : 114.8/200
C : 84.4/200

You can see my solutions to Paper 22 here.

Sir, for the question by transformation by matrix, you sure its 90 anticlockwise? I multiplied 2 matrices I got it 90 clockwise

 

[sasuke474]

If you had to guess, do you think the boundary for A* will go higher or lower than the average? Because I know I put in the amount of effort that would have gotten me full marks last year, but this year the questions were just too confusing like they were in some alien language it's unfair

 

[notnek01]

u will get the whole mark lol... they want that ...

Technically, 1743.845... is not exact so you're meant to round to 3sf. But often you won't lose marks for not following the rule exactly.

 

[Princess Raven]

sir can u like upload it again or something.. couz its like the file is damaged?

 

[notnek01]

Sir for the length of OP5 i wrote it as 3.67 will i getting any mark

You won't get any marks for that answer. But you may get marks for working.

 

[notnek01]

Sir in Perimeter question, I calculate upper bounds and lowerbounds correctly And just added them once(didnt multiply by two )How Much will i loose??

Probably 2 marks.

 

[notnek01]

in question 3d) if we write the coordinates 2.6,3.1
will i get the marks?

Yes.

 

[notnek01]

and in question 10a) if we write the denominator as 3x + 9
how many marks will be deducted?

No marks.

 

[StudentXYZ]

Thank you very much.
I solved the tangent in question 3-d wrong. So will question 3-d(ii) be wrong. I solved the gradient correctly for my wrong tangent.

 

[Mohab88]

thanks alooot u make me happy because isa i will bring A

 

[Shehab_]

Hello. For question 9 b I used 12 instead of 12000 in both sections. However all the steps are correct. How much will I get out of 9 ?