VCE General & Further Maths Question Thread!

[kavmeh]

Hi
Can anyone please help me with question 13 (core) question 9 (number patterns) and question 9 (matrices) from 2014 exam 1
Thank you 

[BakedDwarf]

Hi
Can anyone please help me with question 13 (core) question 9 (number patterns) and question 9 (matrices) from 2014 exam 1
Thank you 

For question 13:
1. Divide the graph into three regions, were the regions have 5, 6, 5 data points respectively
2. Calculate the median value of the first region (3, 8 )
3. Calculate the median value of the third region (14, 8 )
4. Calculate the gradient using m = (y2 - y1) / (x2 - x1)
                                                      = (8 - 8 ) / (14 - 3)
                                                      = 0

For question 9 matrices:
You should know that multiplying a matrix with its inverse results in the identity matrix. That is: A x A^-1 = I
Hence, we know that B is the inverse of A (vise versa)

So, when a question ever asks if something is true, it's best to try them with actual values. Let's set up some matrices
A = [ 2   3]           and         A^-1 = B = [-1  0.5]
       [6    3]           and                           [3     -1]

Just plug these matrices in each answer and see which one yields the incorrect response

[kavmeh]

Thank you BakedDwarf 

[Orson]

Can someone explain Q12 (CORE) from VCAA 2014?

Cheers!

[AngelWings]

Can someone explain Q12 (CORE) from VCAA 2014?

Cheers!

I've actually done this one in detail before and asked anybody who didn't know how to do it to PM me, but I guess I'll put it on the forum for you all, 'cause I'm feeling nice.

Spoiler

The question is the following:
The seasonal index for heaters in winter is 1.25. To correct for seasonality, the actual heater sales in winter should be:
A. reduced by 20%.
B. increased by 20%.
C. reduced by 25%.
D. increased by 25%.
E. reduced by 75%.

So where to begin?
Let's use what we know and what we want. For this, we want to get 1 ("correcting for seasonality" goal) and we know seasonal index is 1.25. We know we want to make the number smaller (1.25 --> 1.00), so we divide: 1/1.25 = 0.80.
This (0.80) is lower than 1, so that's a decrease. It eliminates B and D instantly. We, then, just subtract: 1 - 0.80 = 0.20 to find out how much the decrease was (divided by 100, since it's still in decimal form).
Thus this gives you the result of A.

The same method may be applied to VCAA 2011 Exam 1 Q12, but you must consider the case. If it is obviously an increase, then subtract 1 from the larger result. Note that you still have to apply the 1/(seasonal index) rule, but the last step (the subtraction) is the part it differs. If not, apply as per above.

[n.a]

You guys have worked hard (I assume), so you guys have nothing to worry about. Try your best, breathe, be prepared and smash it out of the park.

While you're on that paper, n.a, have a look at Q9 of the Geometry section.

Yup, surprisingly, I did it correctly! One of those questions that seem hard in the beginning and actually work out in the end, I guess!

And thank you StupidProdigy and BakedDwarf, I get it now. Damned brackets.

[girl1234]

Hey guys, i get a bit confused with questions that give data and ask how it's best displayed? Can anyone help with what each method of displaying data (box plots/bar charts/histogram etc) are used for ??

[Lumierys]

For VCAA 2008 Further Exam 1. Core question 10. What's the difference between multiple choice's D and E?

[kavmeh]

Hi
Can anyone please help me with question 3d and 3e (Number patterns)
and question 1e (graphs and relations)
Sorry it's a bit late but the website wasn't working before 
Thank you

[girl1234]

For VCAA 2008 Further Exam 1. Core question 10. What's the difference between multiple choice's D and E?

D implies it's definitive/will happen whereas E suggests there's an association

hope that helped somewhat, can't really explain stuff too well and it's late

[lifeisnotascore]

In the five number summary, when stating the maximum, can it also be an outlier?

[MightyBeh]

Hey guys, i get a bit confused with questions that give data and ask how it's best displayed? Can anyone help with what each method of displaying data (box plots/bar charts/histogram etc) are used for ??

My understanding:

dotplot/boxplot are for data that have a list of numerical values.
(tried to do an example with tables, but they're not working? )

stem and leaf/ back-to-back stem and leaf is similar, except it retains the numerical values. In a back-to-back stem plot, you have the same type of numerical data but not necessarily the same quality measured over two categories. (eg. Male/Female, test scores)

Barcharts are for measuring the frequency (count or percentage) of an occurrence. (eg. Votes, percentages per candidate)

Histograms are the same thing but with numerical data (eg. Average heat of ovens. Number of family members)

Scatter plots are for bivariate data (so when one variable is linked to another).

Is that all of them? idek at this point

In the five number summary, when stating the maximum, can it also be an outlier?

Yep! (so can the minimum)

EDIT: Oh yeah and good luck for exam 1 and stuff.

[Orson]

I've actually done this one in detail before and asked anybody who didn't know how to do it to PM me, but I guess I'll put it on the forum for you all, 'cause I'm feeling nice.

Thanks so much! Thanks for feelin' nice!

[MightyBeh]

What's the consensus on mean vs. median? Doing a check on my bound reference and it's not there.

Is it just outliers/skew = median, symmetric/no outliers = mean?

[Darkknight26]

Quick Question- When applying a log transformation to linearise the data, do we you natural log or log base 10?