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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: Niskii on September 24, 2011, 07:03:24 pm

Title: Units/Rounding
Post by: Niskii on September 24, 2011, 07:03:24 pm
Hi everyone! Hope the study and holidaying's going well :)

Just a few quick question questions with Methods.

Firstly, in a 1-mark question, if you answer with the correct value do you also have to have the units for it to be marked correct in situations like:


Just looking for a definite answer so I can mark my practice exams accordingly :). I know that it would probably be safer to just put units in all the time, but when I read a question like "find the value for x for which the time to do (something) is a minimum", my immediate interpretation is that answering with the value alone would be sufficient to answer the question, and I generally don't put the units in.

On that note, are there 1/2 marks given?

Also, what's the go with rounding when you're dealing with things such as people and objects where you can't have a fraction of one? If the answer your calc gave you was 43.732 and the question's talking about "how many people..." would you round up to 44 or down to 43 because you don't actually have that extra .268 of a person?

Thanks in advance! :D
Title: Re: Units/Rounding
Post by: Greatness on September 25, 2011, 11:41:16 am
"Average value" application questions (e.g. average height of the cross-section of a hill). Is there a difference in terms of if you need units or not between "Find the average value of f(x)" and "Find the average height of the hill"?
Yeah i would include units, especially if the question is describing a situation

Find the mean and standard deviation (e.g. the mass of something)
Units would be required for the mean? But not standard deviation?

Find the value for x for which the time to do (something) is a minimum
Find the minimum time, in hours, required for (something). If the units are given in the question would you be required to put the units in your answer?
Yep include units for both!

On that note, are there 1/2 marks given?
Nope you only get half marks if one examiner gives you 1/1 and the other 0/1

Also, what's the go with rounding when you're dealing with things such as people and objects where you can't have a fraction of one? If the answer your calc gave you was 43.732 and the question's talking about "how many people..." would you round up to 44 or down to 43 because you don't actually have that extra .268 of a person?
It depends on the context of the question, if you need something to be greater than a certain number then round up.
Title: Re: Units/Rounding
Post by: Aurelian on September 25, 2011, 04:20:48 pm
Quote from: swarley on September 25, 2011, 11:41:16 am
Find the mean and standard deviation (e.g. the mass of something)
Units would be required for the mean? But not standard deviation?

Units for the standard deviation too, I believe :)
Title: Re: Units/Rounding
Post by: paulsterio on September 25, 2011, 05:46:14 pm
"Average value" application questions (e.g. average height of the cross-section of a hill). Is there a difference in terms of if you need units or not between "Find the average value of f(x)" and "Find the average height of the hill"?

Yes, you definately need units for this if the y-axis has applicable units
If it asks for the average value of f(x) and the y-axis has no units, then there's no units required

Find the mean and standard deviation (e.g. the mass of something)
Both Mean and Standard Deviation have the same units as whatever units your Variable (X) has


Find the value for x for which the time to do (something) is a minimum
Your units will be units of time, definately required

Find the minimum time, in hours, required for (something). If the units are given in the question would you be required to put the units in your answer?
You technically don't need units if it's in the question, but you may as well put them, there's no loss :)
Title: Re: Units/Rounding
Post by: Niskii on September 25, 2011, 06:57:35 pm
Cool beans, thanks for all of the answers :) Looks like I'll have to start being super careful with those units!