Sig figs question

[simpsons712]

Hi,

Could someone clarify the appropriate answer for 0.0105-(4.97x10^-3) taking into account sig figs.

Should the question be interpreted as 0.0105-0.00497=0.0055 (based on addition/subtract rule)

or

0.0105-(4.97x10^-3) = 5.53x10^-3

Thanks

[crispix]

i'd like to know this too

[Vincezor]

Hi,

Could someone clarify the appropriate answer for 0.0105-(4.97x10^-3) taking into account sig figs.

Should the question be interpreted as 0.0105-0.00497=0.0055 (based on addition/subtract rule)

or

0.0105-(4.97x10^-3) = 5.53x10^-3

Thanks

If you are given those values in the quesiton, I think you'd go with the lowest decimal point. However that part more appropriately looks like it came from the middle of a back titration calculation, and not a final answer? (I hope). In that case I don't think VCAA would be overly pedantic over which one it would be, and should accept both.

However, I'm not 100% sure :/ I personally wouldn't worry TOO much about this, I don't think I've ever seen a case where such a scenario has occur. Spend more time worrying about the content and not the little things

[simpsons712]

Hey yeah that was the final answer unfortunately, last question of VCAA 2008 infact. :S

[acinod]

I am also incredibly lost in VCAA's 'rules' for significant figures. In the VCAA 2008 Exam, the solution to Question 8aii was 0.0105-0.00497=5.53x10^-3 (0.00553). So in 2008, VCAA did it to the lowest number of significant figures when subtracting values.

However in the VCAA 2009 Exam, the solution to Question 3b was 0.100-0.0200=0.080. VCAA even stated,

Most students seemed comfortable with expressing the result of a multiplication or division to the same number of significant figures as the measurement with the fewest significant figures. They seemed less familar with the rule for addition or subtraction of data where the result should have the same number of decimal places as the measurement with the fewest decimal places.

I asked my tutor and he said to just do it to the lowest significant figures but now I am just totally confused. Can someone please clarify this issue?

[luken93]

I thought somewhere they said that the previous (08) assessment report failed to recognise the addition/sub rule in the report, but did actually mark according to lowest number of DECIMALS.

Don't ask me which one it was, cos I have no idea hahaha

[acinod]

I asked VCAA and they replied with "rounding at the end of a numerical question takes into account significant figures, rather than decimal places."

[jane1234]

I asked VCAA and they replied with "rounding at the end of a numerical question takes into account significant figures, rather than decimal places."

So we don't use the addition/subtraction rule with decimal places?

[dopplereffect]

There is a + or - one sig fig leeway that assessors take into account so don't worry.

[acinod]

There is a + or - one sig fig leeway that assessors take into account so don't worry.

If this is true then we wouldn't have to worry at all

But I'm going to round my final answer to the lowest number of significant figures. NEAP 2011 also rounded to sig figs so I'm not going to worry about the addition/subtraction rule. If we get more people to use this method then hopefully VCAA will allow it.

[cltf]

Unless the question specially states to the correct number of significant figures, then the decimal rule doesn't apply.

[simpsons712]

THANKS !