#### OakMoon!

After the initiative taken by Math_angel in the IGCSE section, I have made this topic for students of O'levels. You can post any question or any problem here and me along with other XPF users will try to help you as soon as possible. This topic is a feasible option as it won't bring a hassle of making new topics for every question and it will also allow the helpers to not miss any of your questions and have one common topic for answering your Mathematics queries.

#### leosco1995

Re: O'level Maths, Addmaths and Statistics help available he

Some moderator should sticky this thread! Also, if no one has any problems I think I might make a thread like this for physics and chemistry.

#### scouserlfc

Re: O'level Maths, Addmaths and Statistics help available he

Sure go ahead and do it,its going to benefit u only.

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Okay... Thanks....

#### abcde

Re: O'level Maths, Addmaths and Statistics help available he

Thank you hamidali391 for creating such a thread. Here's my question: In Oct/Nov 2006 paper 2 (maths 4024:http://www.xtremepapers.me/CIE/Cambridge%20O%20Levels/4024%20-%20Mathematics/4024_w06_qp_2.pdf ), my answer to the last part of the last question comes as 10/447 whereas the er (http://www.xtremepapers.me/CIE/Cambridg ... w06_er.pdf ) states it as 10/449. Anyone please look into this matter!
Secondly, when asked to find values using a graph, are dotted guide lines necessary or can we simply write our answers directly?
Thanks.

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Yeah same question and I want to ask this too... You ppl must have solved such questions in Maths papers... They ask for Angles and sometimes the marks are two so if one just writes the answer and its correct will he get the marks???? Just the answer no detail for it?

#### OakMoon!

Re: O'level Maths, Addmaths and Statistics help available he

I believe the answer in the ER is wrong. It should be 10/447. It must have been a miss print.
You should make the dotted guide lines which allows the examiner to check how you found out the answer. And incase your graph is not properly drawn, he can just check whether you have gotten the correct answer from what you've drawn.

#### OakMoon!

Re: O'level Maths, Addmaths and Statistics help available he

"If working is needed for any question it must be shown in the space below that question.
Omission of essential working will result in loss of marks."
This is written on the first page of the mathematics paper. Which tells you to show working as far as it is possible. There is always a reason behind allocating two marks to an angles question and there is almost always working involved that you should show.

Hopw this cleared.

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Thanks... But how its 10/447? Explain please?

#### OakMoon!

Re: O'level Maths, Addmaths and Statistics help available he

2*10/150*25/149=10/447
Since, one student is chosen first and then the second is chosen, the total number of possibilities for the second selection have to be deducted by one as one student has already been chosen.
While, we multiply by two because either of the two students, <140 or >170, could be chosen first. There are two possibilities as it could be 10/150*25/149 or 25/150*10/149 so we multiply by 2 as the denominator remains the same in both possibilities.

Hope this helped.

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

It did... But er says this...

Even good candidates were apt to forget the factor 2 or to use a
denominator of "150 × 150" in place of 150 × 149.

Doesn't it mean that the denominators needs to be 150 for both? You have used 149 there?? And the marking scheme answer cannot be wrong...

#### OakMoon!

Re: O'level Maths, Addmaths and Statistics help available he

The wording is confusing, it says that the candidates forgot the factor of 2 and used a denominator of 150*150 in place of 150*149 which was wrong, they have told two mistakes and not two forgetfulnesses. Apt here says that the candidate were inclined to 150*150 instead if 149*150. And the question is not in the marking scheme. And who says that marking scheme answers cannot be wrong? We have found answers on this website and proved that they were wrong. It is a miss print in this ER.

#### OakMoon!

Re: O'level Maths, Addmaths and Statistics help available he

And can you please put aside the ER and look at the logic? Such questions come frequently in probability questions.

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Oh ok,,, And Yeah.... I meant ER not MS... And can you please show me those questions? For which the answers are proved wrong?

and yeah I know such questions come... Have seen them.. Same logic....

#### abcde

Re: O'level Maths, Addmaths and Statistics help available he

Agreed with hamidali391!

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Can you tell me about those questions?

#### OakMoon!

Re: O'level Maths, Addmaths and Statistics help available he

They are not mathematics questions. In one question in Biology, that abcde knows about, there were different answers in the examiner report and the marking scheme and the examiner report was contradicting its own answer. It happened once more. @abcde: You were the one who asked those questions. Can you please tell the questions to CaptainDanger? Or guide him to the topic?

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Ok.... Thnx! ???????????

#### CaptainDanger

Re: O'level Maths, Addmaths and Statistics help available he

Thank you!