Rounding Errors

[Unknown_one]

Do we use the rounded values from the question before in long Exam 2 questions?
In some exams they have used it, and in others they have not and they have resulted in different answers.
For example in a Heffernan Exam the difference in answers is from 55.14, to 55.9 degrees.
Or something like that, its about a degree jump.
For VCAA do we use the rounded result from the question before to solve the question after
Thanks

[StumbleBum]

I believe VCAA will accept either answer depending on whether you have used the rounded value or the exact value. However, I would recommend always using un-rounded answers in following questions, as you can be assured that this is more correct. With that being said, sometimes VCAA exams will specify to use the previous rounded answer, so in this case you would obviously use the rounded answer.

[Stick]

Unless the question tells you otherwise, you need to use unrounded figures from previous parts to work out a question. Also, to receive rounding error marks, the source of the rounding error needs to be clear to the examiner, or else you'll receive zero. Hence it's always a good idea to write an unrounded answer and then round it on the next line.

[StumbleBum]

Also, to receive rounding error marks, the source of the rounding error needs to be clear to the examiner, or else you'll receive zero. Hence it's always a good idea to write an unrounded answer and then round it on the next line.

This wouldn't change the amount of marks received I wouldn't think?

If say it was a two mark question, one mark would be method (writing out formulae and plugging in correct values lets say) and then another mark would be for the answer. So if you rounded incorrectly after writing the un-rounded answer, you would still lose a mark; wouldn't you?

[Stick]

For the first time, yes. However, from then onwards in the paper, you will not be penalised at all if you round incorrectly, but only if the source of the error is clear.

[panicatthelunchbar]

so...unrounded answers to use in the next question, then round that answer again?
do you think any way is correct as long as you have the correct method and round off if asked again for the consequential mark??

[StumbleBum]

As a rule of thumb, I would always recommend using unrounded answers. Although VCAA are quite good in the way that they structure the exams, as normally, whether you use the rounded or unrounded answer it should yield that same result. Because they normally make the next question to a lesser amount of decimal points, if any at all. Or they will just specify to use the rounded answer.

[FlorianK]

Why bother using the values that you wrote down?
Your answer will be saved as an unrounded value in your CAS.

[Stick]

^ Yes, there is no need to write down a ten decimal place number or something ridiculous like that in your working out, but on your CAS you need to use the exact answer. Usually I write to four decimal places on the paper in my working out so that the examiner can see I'm not using the previously rounded answer.

[StumbleBum]

Oh that's what you men't FlorianK, I just though it was implied that you wouldn't actually write out the unrounded answer but just simply use it in the next question. I'd normally do what stick said, just go to 4 or so decimal places, but use the exact answer in your CAS.