Physics Frustration [Question]

[Kryolite]

Herro :>

Recently, I've started the Physics A2 Level past papers [CIE] and am doing quite well if I do say so myself ^.^
One thing that really gets me p!ssed off is the marking scheme's answers to calculations.

I'll give you an example: _{9702, S10, Paper 42, Question 1b[ii]}

My faithful calculations gave me an answer of: 6.48 x 10³ ms^-1
However, in their marking scheme the answer is written as: 6.5 x 10³ ms^-1.

If you noticed, they round their answers off to 2 significant figures (1 decimal place). My teachers told me that we should always keep it at at least 3 significant figures (2 decimal places). My question is basically: will they mark my answer and working as wrong?

Perhaps I'm being paranoid but it really is frustrating, especially when you have linked questions (questions that depend on the previous answer you got). In those cases, decimal places can change your answer quite significantly. Does anyone else have this problem? I mean we can't always expect our answer to match the marking scheme's 100%, can we?

I'd appreciate any help and/or advice. Thank you all in advancies
<sub>~ Much Love,
Kry.

PS: I apologize if this in the wrong section or has been asked before.</sub>

[Malak]

Don't round off your answers until the end.

As for the final answer, usually they accept answers within range. I don't think they will penalise you for that unless they have stated in the question how many s.f. they want.

[Kryolite]

Don't round off your answers until the end.

As for the final answer, usually they accept answers within range. I don't think they will penalise you for that unless they have stated in the question how many s.f. they want.

But I don't D:
I always round off my final answer to at least 3 significant figures. In the marking scheme, however, they only give 2 s.f.

Hmm... I hope they do have a range :/
_______________________

_{Good Lord, why are there so many advertisements in my original post?! O__O}

[kaipai]

Good query. very good query.
The significant figure problem at a level phsycis is very significant!
The examiners have bcome very strict. I feel that one needs to understand that not always will the 3 signifcant figure idea work becoz sometiems one gets questions where the data is give only to two significant figures or one significant figure. I guess that one needs to look at the particular quesiton to tell how many signifciant figures are okay.
Moreove, i guess that if there are 2 significant figures mentioned in case of velocity while only 1 incase of time, then acceleration, to my knowledge, could be given to 2 signifciant figure.
Yes it is confusing but all depends on the question...

let me research more before i can finally say something definately...I am at AS level .
thanks