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Standard Math Q+A Thread
dani01:
Hi I'm having a bit of trouble wrapping my head around percentage error/measurement type questions (I know they are practically easy) but for example what would be the absolute error of the number 5.54mm. the formula sheet has 1/2 x precision but how do I find the precision? is it just .05 and then i half that to find the absolute error. so then if i have a number 7.89 the absolute error is the exact same? i think that is what I don't understand.
I get how to find the percentage error of the number but when I type it in to my calculator how do I know where to round off the percentage?
Hope this all makes sense :) :)
RuiAce:
--- Quote from: dani01 on August 06, 2019, 05:24:13 pm ---Hi I'm having a bit of trouble wrapping my head around percentage error/measurement type questions (I know they are practically easy) but for example what would be the absolute error of the number 5.54mm. the formula sheet has 1/2 x precision but how do I find the precision? is it just .05 and then i half that to find the absolute error. so then if i have a number 7.89 the absolute error is the exact same? i think that is what I don't understand.
I get how to find the percentage error of the number but when I type it in to my calculator how do I know where to round off the percentage?
Hope this all makes sense :) :)
--- End quote ---
The precision is basically just how far you go with decimal points. If your measurement is 5.54mm, then they are precise up to the nearest 0.01mm. So the absolute error is then one half of this, i.e. 0.005mm.
With 7.89, sure if you assume that it's also measured in mm. If it were in cm, then your absolute error would be 0.005cm.
I think you get told how far to round with your percentage error.
dani01:
I've been doing some past papers and questions which always come up are those with combinations etc. Was this part of the old syllabus or do I have to know this because I have never done these in class or seen the formulas which are shown in the answers.
Mia-lexa:
--- Quote from: dani01 on August 11, 2019, 03:08:42 pm ---I've been doing some past papers and questions which always come up are those with combinations etc. Was this part of the old syllabus or do I have to know this because I have never done these in class or seen the formulas which are shown in the answers.
--- End quote ---
I think you're referring to probability? For example, you would find questions like: 'A bag contained 4 blue marbles, 3 red marbles and 2 green marbles. If Bob drew one marble and then drew another one. What is the probability that he will draw two marbles of the same colour?'
If this is the type of question you are talking about and you are having trouble understanding it or solving it, I would recommend revising it and asking for help from your math teachers. There are also papers you can find online with worked examples that can help you work closely on a specific subject as such. Probability is part of our current syllabus so it would definitely be worth revising before your final exams. Good luck! ;)
dani01:
--- Quote from: Mia-lexa on September 29, 2019, 01:35:13 pm ---I think you're referring to probability? For example, you would find questions like: 'A bag contained 4 blue marbles, 3 red marbles and 2 green marbles. If Bob drew one marble and then drew another one. What is the probability that he will draw two marbles of the same colour?'
If this is the type of question you are talking about and you are having trouble understanding it or solving it, I would recommend revising it and asking for help from your math teachers. There are also papers you can find online with worked examples that can help you work closely on a specific subject as such. Probability is part of our current syllabus so it would definitely be worth revising before your final exams. Good luck! ;)
--- End quote ---
Hey its all good I was talking about something called permutations and I checked with my teacher a while back and Its nothing I've got to worry about since it is part of the old sylllabus! thanks though
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