How do we know when to use the previous rounded answer or exact value in exam?

[CorkedBoard]

Hi guys,

In the methods exam when there is a question with multiple parts, and the first part asks us to say, round to 4 decimal places, do we use this rounded value or an exact value if required in the next question? (For example, finding the Expected value in part i), and then the second question asks to find the Variance, which could use the E(x) from the previous question).

Also, how strict are the examiners on rounding based on this? Because sometimes, when using an approximate value the decimal places are different compared to when using an exact value.

[james.358]

For every single calculation, always always use the exact value! (Unless the question tells you to use a specific value) If you don't have an exact value to work with, use wayyy more decimal places than necessary just in case. The only time you write a rounded value is at the very end, when you have solved the question. Unless otherwise asked for, put your answers in exact form. 

The examiners are very strict about this. Unlike Chemistry or Physics, where a range of values would be accepted, in VCE Maths there is only one correct answer.

Hope this helps,
James