VCE General & Further Maths Question Thread!

[AngelWings]

hey need help with Q7 of matrices in 2017 NHT
how do you interpret two-step dominances??

While I don't entirely understand this and don't think I've ever encountered this either, I do have a resource for you right here from Engage Education.
Sorry I couldn't be of more help!

[Mattjbr2]

I circled the one that I think is the answer and pointed to the one which MAV thinks is correct. Who's right?

[emmaline]

Hi, would really appreciate if someone could help with this question. I don't understand why it's C and not B. Thanks!

[anicawajswelner]

CAN SOMEONE PLZ EXPLAIN THE SLIDING LINE TO ME?!!?!?!?!?!

[emmaline]

Oh the question didn't attach

[Eric11267]

Oh the question didn't attach

Sorry, I don't do further maths so take what I say with a grain of salt.
Both B and C will have that general shape and pass through the point (4,1/10). The only thing I would say is maybe look at the graphs scale. At x=1 the y value is quite clearly under 1. Subbing in x=1 would give you 8/5 for B and 2/5 for C so I guess it would be C for this reason. Anyone feel free to correct me because I'm clueless about further maths

[BlinkieBill]

I circled the one that I think is the answer and pointed to the one which MAV thinks is correct. Who's right?

first Q: MAV is correct since the two variables are not completely random
2nd Q: r=.68 is moderate, not weak
and the word 'tends' indicates that it is not an exact causal relationship,  so you shud try to find answers with the word 'tends'

[Mattjbr2]

CAN SOMEONE PLZ EXPLAIN THE SLIDING LINE TO ME?!!?!?!?!?!

The objective function has a gradient. Place your ruler on the graph parallel to that gradient. Now slide your ruler up and down the graph while maintaining that gradient. The last vertex to touch your ruler while you're sliding up/down is the maximum/minimum point. If your ruler touches an edge (parallel to your ruler), then all points along that edge are valid maximum/minimum values of the objective function.

Oh the question didn't attach

Both are correct if you don't have a CAS or if the graph isn't perfectly to scale. But n=1 (i.e. C) is more accurate if you graph both n=1 and n=2 on your CAS.

first Q: MAV is correct since the two variables are not completely random
2nd Q: r=.68 is moderate, not weak
and the word 'tends' indicates that it is not an exact causal relationship,  so you shud try to find answers with the word 'tends'

Thanks!

[AngelWings]

I circled the one that I think is the answer and pointed to the one which MAV thinks is correct. Who's right?

Question 11 shows that there is a trend there that appears to have a moderate correlation. There is likely some sort of explanation, making C more correct.
Question 6 is B. Sorry man. An r value (correlation coefficient) of 0.68 is positive and of moderate strength, not weak. This is one of those where you have to watch the wording to get right.

A little explanation...

Options A and D are incorrect because it's not a coefficient of determination. C is wrong because it's not "causal", it's an association/ correlation. Math doesn't work quite the way E says it to be.

Hi, would really appreciate if someone could help with this question. I don't understand why it's C and not B. Thanks!

Spoiler

There's a bit of a trick to this question because it's not actually clear, but the difference is in the slope. Yeah, that's the tricky part. If you go back and graph the two graphs into the calculator, you'd realise there's a solid gap between x = 0 and x = 0.3 for Option B, which doesn't appear in this graph. Measuring this graph, you can see that the gap is really small, like smaller than 0.3. Luckily, VCAA are usually clearer than this. 

I just realised I was beaten to the punch. Oh well, hopefully these help somebody.

[Creamysnow]

CAN SOMEONE PLEASE EXPLAIN THIS QUESTION!!!

[Mariamnourine]

Hi, would really appreciate if someone could help with this question. I don't understand why it's C and not B. Thanks!

So they gave you the point. y=4 and x=1/10

Literally substitute x into the equation and see if you get y=4. when I tried for B, The answer was 160, when I tried for C, the answer was 4, which is correct.

[Opengangs]

CAN SOMEONE PLEASE EXPLAIN THIS QUESTION!!!

Use the fact that triangle ABD and triangle ABC are similar (they are equiangular).
This implies that the ratios of sides are in proportion.
Thus, the area of triangle ABC is (40/24)^2*100 ~~ 278cm^2

[Angelx001]

Can someone explain 2008 exam 1 question 9??? (core!!)

[AngelWings]

Can someone explain  2008 exam 1 question 9??? (core!!)

I assumed VCAA E1 2008 Core Q9.

Spoiler

You should be looking at the y axis (weight) and finding the median of the 12 points from there, so look at the 6th and 7th points and get their average. You must count from bottom to top of the y axis in order of their y coordinates.
The points give y values of 430g and 450g, so their average is 440g.
The answer is C.

[hmdeadas]

HOW do i do correction for seasonality?
QUESTION was - the seasonal index for sales in winter is 0.75
To correct seasonality, the actual sales in winter should be
a)increased by 25%
b) reduced by 25%
c)reduced by 33%
d)increased by 33%

I have no idea how to do it and thought it was c, but the answer is D