sf in maths (1 Viewer)

[neuvie]

when doing questions such as application of exponential decay, and the answer isnt really in exact form but has a lot of dp (such as ln3/6=0.183...), how many sf do i answer to if it is not specified? because sometimes i look in hsc answers and it gives like 2-3 dp and it is so confusing, i dont want to answer it wrong.

 

[Average Boreduser]

when doing questions such as application of exponential decay, and the answer isnt really in exact form but has a lot of dp (such as ln3/6=0.183...), how many sf do i answer to if it is not specified? because sometimes i look in hsc answers and it gives like 2-3 dp and it is so confusing, i dont want to answer it wrong.

I mean if they don't specify, it's really up to you lmao. I usually would go w 2dp. but extend that more if that value would skew the decay solution by a significant mark.

 

[carrotsss]

give exact answers unless told otherwise

 

[neuvie]

give exact answers unless told otherwise

what if it's like really messy? like with even more ln and e and stuff that just doesnt really make it look like a proper answer

 

[carrotsss]

what if it's like really messy? like with even more ln and e and stuff that just doesnt really make it look like a proper answer

you don’t get marked on how nice your answer looks, you get marked on how correct it and your working is

 

[femboys4life]

what if it's like really messy? like with even more ln and e and stuff that just doesnt really make it look like a proper answer

You can always just give both to make life easier for the marker

 

[iloveeggs]

typically when its unspecified, you leave it in exact value form whenever you can. being messy is not a problem as long as it is simplified as much as you can.

in some situations when they ask to find a certain quantity, e.g. time or length AND i don't need to re-use that value for any further calculation, i will show the exact value and then round to 1 or 2 decimal points or lowest amount of significant figures specified in the question. but this is only when the exact value is bulky and it would make more sense to show it as a decimal instead. i'll just show a random example of my process when i do this:

x=1/e (exact value) --> x=0.3678.... --> x=0.37m (2d.p.)

my school accepts this when the question doesn't specify and the decimals and rounding is reasonable as long as i show the exact value as well. i also HAVE to write what i rounded to and show what it was before rounding with ...

 

[cossine]

what if it's like really messy? like with even more ln and e and stuff that just doesnt really make it look like a proper answer

Ignore carrotsss.

The key point is that you demonstrate sufficient understanding. The only possible scenario you will get marks deducted if is a question ask for the exact answer and you provide an approximate answer.

There is also intermediate rounding error but most likely you will not encounter that issue in the HSC as most questions will state "correct to two decimal places". i.e. you can use the corrected answer.

If you like you can look at the official solutions to the HSC papers on NESA to get an idea on how to set your work

 

[carrotsss]

Ignore carrotsss.

The key point is that you demonstrate sufficient understanding. The only possible scenario you will get marks deducted if is a question ask for the exact answer and you provide an approximate answer.

There is also intermediate rounding error but most likely you will not encounter that issue in the HSC as most questions will state "correct to two decimal places". i.e. you can use the corrected answer.

If you like you can look at the official solutions to the HSC papers on NESA to get an idea on how to set your work

I agree that you can put it either way esp in advanced but imo if you’ve already got the lines of working there you might as well leave it that way, and putting into your calculator can leave room for errors and waste time

 

[Average Boreduser]

imo if your exact answer is crazy insane to the point where you can't sort of approimate it in your head, its probably better to give an approximate IN ADDition to the exact ans to secure yourself.

 

[wollongong warrior]

when doing questions such as application of exponential decay, and the answer isnt really in exact form but has a lot of dp (such as ln3/6=0.183...), how many sf do i answer to if it is not specified? because sometimes i look in hsc answers and it gives like 2-3 dp and it is so confusing, i dont want to answer it wrong.

just give exact expression (whatever exponential, log etc) and give 2dp
e.g. x = ln(2312)/3 ≈ 2.58