VCE General & Further Maths Question Thread!

[chenay0123]

Hey, can someone show me how to put this question in matrix form? thanks

[val265]

Hey guys,
Just wondering in Bearings if it says find A from B  do we start at B?

[Aaron]

Hey guys,
Just wondering in Bearings if it says find A from B  do we start at B?

Yes [as long as it says that, not the other way around]

If there's a specific question, please post it (so that members on here understand the full context of the question).

[Sine]

this is one of those "tricks" that also comes up in spec which many people trip up on so make sure to check

[val265]

Hey guys what is the formula of a major segment for spherical geometry?

[clarke54321]

Hey everyone,

Can someone please explain to me why the mean is greater than the median for positively skewed data and vice versa for negatively skewed data.

Thanks very much! 

[Jakeybaby]

Hey everyone,

Can someone please explain to me why the mean is greater than the median for positively skewed data and vice versa for negatively skewed data.

Thanks very much! 

Let's consider two separate samples taken:

Sample 1: 1 3 7 3 2 3 6 3 2 4 3 5 7 3 1
Sample 2: 7 7 6 3 8 9 7 6 4 2 2 6 8 9 6

Organising the samples in ascending order we get:

Sample 1: 1 1 2 2 3 3 3 3 3 3 4 5 6 7 7
Sample 2: 2 3 4 6 6 6 6 7 7 7 8 9 9 9

We can see that for sample 1, there are more values towards the negative end of the distribution.
Hence, we see a distribution which looks similar to the following:


We can see from the ascending ordered sample that the median for Sample 1 is 3.
Through some simple calculations, the mean is 6.

And then from Sample 2, we see that there are more values at the higher end (towards the positive end). Hence:

The median for Sample 2 is 6.47 and the mean is 7.
 
If we think about it, it is more likely for a data value to occur at the lower end of the scale, due to the fact that more values occur at the lower end. The mean calculates the average of all the values, this also means that the mean is affected by outliers, whereas the median is uneffected by outliers, hence, the mean is always going to be larger in unimodial distributions.

The mean is pulled in the direction of the extreme scores or tail (same as the direction of the skew)

So, for the general rule of thumb, the mean always occurs at the same end of the skew.

[Manige123]

Urgently need help with this question, sac is tomorrow! (Liner programming)

A maker of blended whiskey buys its raw material from three supplies: McAllister, McBride and McCallum. THe maker wishes to purchase a total of 200 litres of whiskey from the three suppliers. The whiskey must contain a minimum of malt and barley. Each suppliers minimum amounts of malt and barley are shown:
McCallister: 7% Malt
McBride: 2% Malt
McCallum: 5% Malt
Minimum amount of ingredient allowed: 4%
x= amount of whiskey bought from McCallister, y= amount of whiskey bought from McBride and 200-x-y = amount of whiskey bought from McCallum.
Define the constraint inequation caused by the restriction on Malt.

answer is 2x-3y > or = to -200.

I know how to do these types of questions and for some reason once i reach 2x-3y, my equation is something like 2x-3y+100<4

PLEASE HELP MUCH APPRECIATED THANKS IN ADVANCE

[Drewballs]

So this is the only way I can find that answer is if you multiply the 4 by 200 (4% for each litre of whisky purchased)

7x+2y+5(200-x-y) > or = to 4 x 200
7x+2y+1000-5x-5y> or = to 800
7x-5x+2y-5y+1000> or = to 800
2x-3y+1000> or = to 800
2x-3y> or = to  -200

[Hydroxyl]

This is a question from the Sample exam.

Consider the following four statements. A permutation matrix is always:
I a square matrix
II a binary matrix
III a diagonal matrix
IV equal to the transpose of itself.
How many of the statements above are true?
A. 0
B. 1
C. 2
D. 3
E. 4


The answers say C, which is 2. But I've done some calculations and found that Statement IV (A permutation matrix is always equal to the transpose of itself) is true.

I'm confused about this..

Anyone that can help, it would be appreciated.

Thanks

[Kimahso]

This is a question from the Sample exam.

Consider the following four statements. A permutation matrix is always:
I a square matrix
II a binary matrix
III a diagonal matrix
IV equal to the transpose of itself.
How many of the statements above are true?
A. 0
B. 1
C. 2
D. 3
E. 4


The answers say C, which is 2. But I've done some calculations and found that Statement IV (A permutation matrix is always equal to the transpose of itself) is true.

I'm confused about this..

Anyone that can help, it would be appreciated.

Thanks

I think Option 4 is only true for 3x3 permutation matrices. For example a 4x4 permutation matrix can have 1s in row 1 column 2, row 2 column 3, row 3 column 1 and row 4 column 4 and the transpose is obviously not the same.

Hey, can someone show me how to put this question in matrix form? thanks

You make C and R both the same variable, for example y, as they are both costs. And then you keep n as number of jeans and solve the simultaneous equations.

[ayesha2011t]

Hey guys
If I need to make a boxplot and a I have outliers on either ends of the boxplot, what will my min and max value be? Do my tails go up to the value in the lower fence which is the minimum and the same for the upper fence?

[clarke54321]

Hey guys
If I need to make a boxplot and a I have outliers on either ends of the boxplot, what will my min and max value be? Do my tails go up to the value in the lower fence which is the minimum and the same for the upper fence?

Hey,

If you have outliers, these will count as your min or max value. If you don't have outliers, the ends of the tails will be your max and min.

I hope that answered your question! 

[ayesha2011t]

Hey,

If you have outliers, these will count as your min or max value. If you don't have outliers, the ends of the tails will be your max and min.

I hope that answered your question! 

That helped!
What if I have outliers, where will my tails extend to?

[clarke54321]

That helped!
What if I have outliers, where will my tails extend to?

If you have outliers, your outliers will be beyond your tails.

However, in some circumstances, you may be given a diagram of a box plot where you have single points beyond your tails. In this case, you cannot just assume that they are outliers. Here, you must apply the upper and lower fence formula (Upper Fence: Q3+1.5*IQR and Lower Fence Q1-1.5*IQR) to work out if they are outliers.