VCE Methods Question Thread!

[LiquidPaperz]

Finally, in terms of circle symmetry - because is one full revolution, so if you add that full revolution, you're just going to end up back where you started.

so that will land me in quadrant 1 if im correct? where cos,tan and sin is positive.

I just dont get where you said it is sin(180+theta)? isnt it just sin(theta) in the first quadrant, the sin(180+theta) is in the third quadrant, because the original question was cos(7pi/3) = cos(2pi+pi/3), and pi/3 is 60 degrees, so ill be at 420 degrees which is 1st quadrant.

Hopefully you understand what im trying to say.

[keltingmeith]

so that will land me in quadrant 1 if im correct? where cos,tan and sin is positive.

I just dont get where you said it is sin(180+theta)? isnt it just sin(theta) in the first quadrant, the sin(180+theta) is in the third quadrant, because the original question was cos(7pi/3) = cos(2pi+pi/3), and pi/3 is 60 degrees, so ill be at 420 degrees which is 1st quadrant.

Hopefully you understand what im trying to say.

Correct - you will be in the first quadrant.

I believe you're being a bit mistaken - I was referencing sin(-135) - not the question with cos(7pi/3).

[knightrider]

Does anyone know how to find minutes and seconds on the cas on the casio classpad

for example does anyone know how you would do sin(35degrees30minutes) on the casio classpad calculator

[LiquidPaperz]

you probably dont need the question for this. But with transition matrix why, (when the formula is Sn = T^nSo) if its 4th week dont you do T to the power of 4 and not 3. I remember my teacher saying something about this in class but i didnt listen, cause i was doing something else, but doing checkpoints i havent seen this come up.

[soNasty]

well i think t^3 would mean 'at the END of the 3rd week', so that corresponds to the BEGINNING of the fourth week

[HEN_iP]

The probability that Perdita will phone Faith is 0.3, and the probability that Hugh will phone Faith is 0.2. If these events are independent, what is the probability that either Perdita, Hugh or both will phone Faith?

Not entirely sure what it's asking...

[soNasty]

The probability that Perdita will phone Faith is 0.3, and the probability that Hugh will phone Faith is 0.2. If these events are independent, what is the probability that either Perdita, Hugh or both will phone Faith?

Not entirely sure what it's asking...

is the answer 0.56?
if so, i got that from just adding 0.3+0.2+(0.3*0.2)=0.56

[plato]

Does anyone know how to find minutes and seconds on the cas on the casio classpad

for example does anyone know how you would do sin(35degrees30minutes) on the casio classpad calculator

In degree mode, just enter it as sin(35+30/60) since 30 minutes is 30/60th of a degree.
But you will not be asked to work in degrees and minutes (and seconds) in the exams - just work in decimal degrees.

If you must convert decimal degrees back to degrees, minutes and seconds (DMS) for some reason outside the syllabus, look in the catalog of your calculator for something like toDMS

[plato]

is the answer 0.56?
if so, i got that from just adding 0.3+0.2+(0.3*0.2)=0.56

P = Perdita will phone Faith
H = Hugh will phone Faith
Pr(P) = 0.3
Pr(H) = 0.2

Pr(P or H or both) = Pr(P U H) = Pr(P) + Pr(H) - Pr(intersection of P and H)
You actually added the intersection.
Pr(P U H) = 0.3 + 0.2 - 0.3x0.2 = 0.44


A much quicker way is to just use 
Pr(P or H or both) = 1 - Pr(neither of them will phone Faith)
= 1 - (intersection of P' and H')

Pr(H')=0.8
Pr(P')=0.7

Pr(P or H or both)
= 1 - (intersection of P' and H')
= 1 - 0.8 x0.7
= 0.44  as above.

[Blondie21]

For the anti diff of ,

why is the answer -ln|2x-5| + c and not -ln|5-2x| + c??

[keltingmeith]

you probably dont need the question for this. But with transition matrix why, (when the formula is Sn = T^nSo) if its 4th week dont you do T to the power of 4 and not 3. I remember my teacher saying something about this in class but i didnt listen, cause i was doing something else, but doing checkpoints i havent seen this come up.

The question would help, but I'm assuming it was something like this:

In the question, it would've said, "in the FIRST week, something happened" or " the probability of something happening in the FIRST week is x and y". The language here is very important.

You see, the first week refers to state 1, or S1. However, in this case, the first week IS the initial state, S0. So, you have to bring everything down one to fix this. That means that the fourth week is now the third state (S3) instead of the fourth state.

Similarly, if we started from the tenth week, then the eleventh week would actually be S1, as the tenth is now S0.

For the anti diff of ,

why is the answer -ln|2x-5| + c and not -ln|5-2x| + c??

They're the exact same thing - recall the definition of the modulus:

[LiquidPaperz]

heres the question, it said initially so i assumed no time had elapsed

[Eugenet17]

http://gyazo.com/676017328d1d0ad44b832d6645418019

To come up with the end result of Pr(3<X<6), are you supposed to round up/round down the values ( eg. 2.2465<X<6.0497)? some questions round up and some round down, im really confused

[keltingmeith]

heres the question, it said initially so i assumed no time had elapsed

Yep - so, initially refers to the first trip, not the zero'th trip. Hence, my earlier explanation.

EDIT: As an aside, the methods course doesn't consider 3x3 transition matrices for markov chains (however, Further considers up to 4x4, so watch out for that). If you see questions like that, don't worry, just skip it - you can't be asked about those.

http://gyazo.com/676017328d1d0ad44b832d6645418019

To come up with the end result of Pr(3<X<6), are you supposed to round up/round down the values ( eg. 2.2465<X<6.0497)? some questions round up and some round down, im really confused

So, discrete data can be tricky in this instance. When you have the case of Pr(a < X < b), you always round INWARDS. So, let's consider the case of . If you round the 4.5 up, you're no longer consider JUST when , you're also consider the values when X is between 4.5 and 5. For discrete data, the points between 4.5 and 5 don't exist - but 5 does, so you've added a whole extra variable. So, to escape counting that extra variable, we must round inwards, so we'd get .

This is only for discrete data - for continuous, you don't round at all, because continuous data can be between whole numbers (which is the basic definition of continuous data).

[LiquidPaperz]

Yep - so, initially refers to the first trip, not the zero'th trip. Hence, my earlier explanation.

so
S1 = T^1So is first trip
S2 = T^2So is second trip
S3 = T^3So is third trip
S4 = T^4So is fourth trip

i dont get how S4= t^3So is fourth trip? am i missing something