Technical Questions

[dekoyl]

1. Kinda me being paranoid again but: Are tree diagrams a MUST when doing conditional probability questions? I didn't draw a tree diagram for the  question about the Cino and Dandy cinemas yesterday.. so will I lose a mark for that?

2. Say the question used the variable instead of the normal . After finishing my paper I then realise I've been using instead of for the whole question. Could I right at the start of the question Let x = t and not lose any marks?

Thanks.

[MikeOxlong]

to ur first point... i dont think they mind how u get the answer as long as its a plausible way of gettn to it.. thats why its 'methods'

and to ur second Q.. NO idea =)

[shinny]

1. ...draw a Markov Chain? You mean tree diagram? Well for that, I don't see why you wouldn't but I still assume not. As long as you had adequate working out I guess.

2. Yes, but you'll have to still give all your final answers in terms of t I'm pretty sure.

[dekoyl]

Fixed and thanks.

I didn't draw one because I just don't. I suck at drawing them too. They come out to be big pieces of wonky crap.
Mmm hope they don't take a mark away. I'm on the verge of crossing the <A+ border. Damn A+ cut off.

[shinny]

I'd at least write the Pr(CCD)+Pr(CDC)+Pr(DCC) step in, rather than jumping straight to numbers.

[Athomas]

I'd at least write the Pr(CCD)+Pr(CDC)+Pr(DCC) step in, rather than jumping straight to numbers.

Yay something I did right! LOL.

[dekoyl]

I'd at least write the Pr(CCD)+Pr(CDC)+Pr(DCC) step in, rather than jumping straight to numbers.

Oh yeah I did that Good good. *phew*

[dekoyl]

Another one..

Is there a need to do Bi~(N,p) and N~(i.forgot.what.goes.here) when doing normal and binomial questions?

[Glockmeister]

no

[dekoyl]

Thanks Glockmeister.
Sorry I didn't put this up before but..

1.Sand falls from a box at a rate of and there's . So that'll take 6 seconds for it to be empty.
But why does the answer say it takes seconds?

So basically what I'm asking is.. are we meant to consider things like this (inconsistent flow rates)? I've never come across anything like this.

2. The question asks "how many rabbits...." and I wrote 7.4 which was wrong (answer was 7). Again, are we meant to consider what's physically possible and what's not, even if the question doesn't ask to "round to the nearest integer"? The language can be quite confusing some times.

[Glockmeister]

1 I wouldn't imagine that they will consider incosistent flow rates/ Put simply, you won't get that question in a VCAA exam.

2. Yes, if it asks for something that is discrete, you must consider what is physically possible. This is because .4 if a rabbit is impossible unless you kill the rabbit and divvy it up. Now, VCAA does not want to get into trouble with the PETA or ALF people. They don't want to have their headquarters blown up.

Seriously though, you would be mark wrong if a VCAA paper happens to have that type of question.

[Collin Li]

If it asks for the expected value of a discrete distribution, do not round.

If the question is phrased like "what is the fewest number of rabbits such that...", then you should round.

[Lulu]

hah this might sound silly but,

let's say if you get a question like:

t=number of days for something

Then you get an answer of t= 16.342, and it asks you to round to the nearest hour, how would you round?

or could you just write t=16 days and 8 hours?

[dekoyl]

^Yeah I'd write 16 days and 8 hours.

I have another one :

I've come across questions where they ask you to sketch a graph then the next question is related to the graph (i.e. you can work out the answer from the graph). If I do some working out on the graph before (very light sketches), will they take the very light sketches into consideration? Or ignore it as just working out?

Ta.

[MikeOxlong]

^Yeah I'd write 16 days and 8 hours.

I have another one :

I've come across questions where they ask you to sketch a graph then the next question is related to the graph (i.e. you can work out the answer from the graph). If I do some working out on the graph before (very light sketches), will they take the very light sketches into consideration? Or ignore it as just working out?

Ta.

yea ive wanted to know that to... like if you have to sketch a graph and then the next qquestion asks you to find the area under the curve can u shade the graph in and stuff???