Probability notation

[kenhung123]

What do examiners generally expect with probability notation? I get annoyed sometimes when I need to define a variable per question such as in 3a) X=number of successful throws and then in b) Y= number of functioning computers just so I can use the notation Pr(X>4) or something like that. I understand its useful if there is like 3 questions involving the variable X or Y but those can keep changing makes it a bit tedious

Is it OK to just use the words directly such as Pr(more than 4 successful throws)=?

Perhaps you have a better method?

[akira88]

Surely writing Pr(X>4) isn't too time consuming or hard But I understand what you're asking.... it might be allowed. But then again, if you can write it mathematically, why wouldn't you?

[kenhung123]

Oh, I am not hassled with writing the Pr(X>4) but in order to do that, I need to define the variable X right?
Also it sometimes worries me as to whether the way I define the variable fits into the question so yea, its quite annoying!

[akira88]

Oh, I am not hassled with writing the Pr(X>4) but in order to do that, I need to define the variable X right?
Also it sometimes worries me as to whether the way I define the variable fits into the question so yea, its quite annoying!

Ah yeah, makes sense

[naved_s9994]

I reckon Pr(> 4 successful throws) should be fine too.

Actually, no it is not fine!
In the study design when laid out in 2006, they specifically have mentioned in
there that it is Maths, not English...and what you had done above, would
"not be awarded any marks". 

[m@tty]

Really? In the study design? I've never heard of that before...

[kenhung123]

Wow! Actually I realised (lol) that the questions usually say T is in minutes and usually you can just say Pr(T>4) or something without needing to define. I think you only need to define with binomial so I guess its alright..

[Yitzi_K]

What about on the calculator paper writing something like Binom PDF (6,0.2,3) or something like that? Is that acceptable as working if the question is for >1 mark?

[kenhung123]

1 mark doesnt need working so I think you don't even need to bother with that

[f.sharp]

yea, state ur n,p and x values to be safe.

its a tech active paper so doubt they'll be overly stringent.

[Yitzi_K]

1 mark doesnt need working so I think you don't even need to bother with that

I said for more than one mark...

[f.sharp]

Do you say like:
Let event A be "number of bullseyes"

Then use Pr(A>3) ?

yessir.

[Chavi]

For 1 mark question on the 2nd exam, just use your calc to write down the answer.
Anything more than 1 mark requires you to show working. If you check the examiner's report for Methods, you'll find that they ask not use calculator notation, so it's probably safest just to write everything out.

[stonecold]

^My teacher is so full of shit...she just told us to write out what we do in the calculator.

She also said that the angle between two lines/curves is 'no longer examinable.'

Should I believe her?

[Chavi]

^My teacher is so full of shit...she just told us to write out what we do in the calculator.

She also said that the angle between two lines/curves is 'no longer examinable.'

Should I believe her?

For the sacs, yes. For the final exam, no.