# An appropriate degree of accuracyWatch

This discussion is closed.
#1
Can anyone offer some more precise definitions?

I'm doing past D2, P4, P5, M3 papers, and it seems to me that "An appropriate degree of accuracy" means something quite different for D, P, M papers, and it seems pointless to lose a mark for not grasping an implied guideline.

D is OK. Integers and vulgar fractions.

P and M are sometimes problematic. When an "exact value" (i.e. leave in surds, Pi, etc.) is not specified, or implied (for example, leave v as a root in circular motion qs.), what do you go for? Every time I leave an answer correct (or wrong ) to 2 d.p., the mark scheme goes for 3 s.f., and vice versa! What about 2d.p. if >0 and 3 s.f if <0 ?

Has anyone seen or been given exact guidance?

Aitch
0
13 years ago
#2
Normally its 3sf... That's what i always put it to eg 5.47 or something. Most of the time you can't put it to more significant figures than the numbers you're using (i think) because when i got my M1 paper back that's what i got marked down for on some questions.
0
13 years ago
#3
(Original post by Aitch)
Can anyone offer some more precise definitions?

I'm doing past D2, P4, P5, M3 papers, and it seems to me that "An appropriate degree of accuracy" means something quite different for D, P, M papers, and it seems pointless to lose a mark for not grasping an implied guideline.

D is OK. Integers and vulgar fractions.

P and M are sometimes problematic. When an "exact value" (i.e. leave in surds, Pi, etc.) is not specified, or implied (for example, leave v as a root in circular motion qs.), what do you go for? Every time I leave an answer correct (or wrong ) to 2 d.p., the mark scheme goes for 3 s.f., and vice versa! What about 2d.p. if >0 and 3 s.f if <0 ?

Has anyone seen or been given exact guidance?
Aitch
well i've looked on recent mark schemes and sometimes the answer gives speeds to only 2sf instead of 3sf. The answer says "23, but accept 22.5" or something like that. My physics teacher told me to always give answers to the same number of sig figs as the least accurate of the data in the question, e.g. the M papers tell you to use g as 9.8 instead of 9.81, so that might be the reason. Although you never can tell, so I always quote to 3sf.
0
13 years ago
#4
(Original post by Aitch)
Can anyone offer some more precise definitions?

I'm doing past D2, P4, P5, M3 papers, and it seems to me that "An appropriate degree of accuracy" means something quite different for D, P, M papers, and it seems pointless to lose a mark for not grasping an implied guideline.

D is OK. Integers and vulgar fractions.

P and M are sometimes problematic. When an "exact value" (i.e. leave in surds, Pi, etc.) is not specified, or implied (for example, leave v as a root in circular motion qs.), what do you go for? Every time I leave an answer correct (or wrong ) to 2 d.p., the mark scheme goes for 3 s.f., and vice versa! What about 2d.p. if >0 and 3 s.f if <0 ?

Has anyone seen or been given exact guidance?

Aitch
most papers say on them answers to 3sf unless specified. but when working with angles (in pure) if there is an answer a[pi]/b with integer a,b they like that. if the answer (in pure) can be put in surd form they want that. from my experience mechanics tend to want 3sf all the time and i've never been marked down for using three sf (unless the question specified otherwise)

d modules seem to like ridiculous significant figues, and numerical methods of integration for ODE's and 2DE's also like 5 or 6 dp...
0
#5
Since three of you significant figures seem to go for 3 sig. figs. ...

Good enough for me!

Thanks

Aitch
0
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