2011 Further Maths Questions

[StoneCutter]

Time for the questions thread where the geniuses can help out the lesser gifted 

I'm completely stumped on something this is my five finger summary: Min-7, Q1-10, Median-11, Q3-15, Max-25

Now the answer says that 25 is an outlier, but I want to know how to check so I done the outlier test which is Q3+1.5*IQR. So in this case it would be 15+1.5*5=82.5, but 25 doesn't lie above 82.5? Massive brain fade on this one guys came from methods so stuff is kind of new to me.

[jasoN-]

15 + 1.5 x 5 = 22.5
BODMAS <- LOL

[StoneCutter]

15 + 1.5 x 5 = 22.5
BODMAS <- LOL

Oh dear haha massive brain fade like I said, thanks. How much effort did you put in to get 50 for Further?

[jasoN-]

Being realistic i did 0 vcaa papers to completion.
The only revision I did was in class (probably 10 exam papers), at home i wouldn't bother

[StoneCutter]

Just came across something new which wasn't in year 11. The three median line, I'm confused with the y-intercept. In the shitty example they have in the book it shows the y-intercept being pretty much the lowest dot on the graph aligned to the y-axis to give you the y-intercept. But for 5D Questions 3. a-d for those who have the textbooks in the answers section for those questions it's got the y-intercept as being different to what the lowest dot aligns with even a -2 pops up even when there's no -2 on the y-axis. Is the book wrong or the noob?

[Hodgeyhodgey]

Exercise 5B, Question 7:
The book says the intercept (a) = -2.6 and yet, I keep getting -2.7

Working:
a = mean of y - b*mean of x
   = 14.82 - 0.73*24
   = -2.7

[Streaker]

Just came across something new which wasn't in year 11. The three median line, I'm confused with the y-intercept. In the shitty example they have in the book it shows the y-intercept being pretty much the lowest dot on the graph aligned to the y-axis to give you the y-intercept. But for 5D Questions 3. a-d for those who have the textbooks in the answers section for those questions it's got the y-intercept as being different to what the lowest dot aligns with even a -2 pops up even when there's no -2 on the y-axis. Is the book wrong or the noob?

Here's the rule:

1. Count up how many points exist on the graph, then divide them equally into three sections (or if there is something like 14 points then arrange them in a 5,4,5 - as long as the two outside numbers are the same)

2. Counting the points from top to bottom, as well as from left to right, you should be able to find a common median ('middle point') for each section. If you get a group of points in a section like this (let's call the first point on the left "1", the highest point "2" and the last point on the right "3")...


              *
                     *

     *

...then you will notice that there are different medians when you apply the rule I used earlier about counting from top to bottom and left to right. To counter this, scribble in an imaginary point where this median would actually exist (at the bottom of point "2", but in line with point "3"). This is your median point for that section. I really hope this made sense.

3. Grab your ruler and make sure the median point in the FIRST and THIRD section are in line with each other, then shift the ruler one-third of the way towards the median point in the SECOND section. Plot a line.

There's your three-median line. Don't worry about trying to memorising it through working out y-intercepts etc. that's just plain confusing. Follow the three steps above and you'll be sweet.

[_avO]

Alternatively, another method to find the three-median line equation with complete accuracy is by using formulas

        m(x3-x1)=y3-y1 and
       c=((y1+y2+y3)-m(x1+x2+x3))/3

where y1 = y median of the left section, y2 = y median of the middle section, x1 = x median of the left section

no ruling necessary

[ech_93]

For the following pairs of sample data sets, find the mean and standard deviation.
Set A: 1, 1, 1, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8, 9.
Set B: 1, 1, 1, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8, 15.

I know how to do the mean, but wtf is standard deviation and how do you find it?!

[onur369]

Instead of fucking up your brain by doing it manually. Plot these numbers into the statistics section of your calculator, then do one-variable stat calculations. It will give you the Five number summary ( MinX - Q1- Med-Q3- MaxX)  Also should have standard deviation in the list. I think it went by sn^-1

[iNerd]

For the following pairs of sample data sets, find the mean and standard deviation.
Set A: 1, 1, 1, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8, 9.
Set B: 1, 1, 1, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8, 15.

I know how to do the mean, but wtf is standard deviation and how do you find it?!

Range/4. I think. Wait for confirmation.

[ech_93]

Haha, thanks onur369!
Could you or anyone else tell me how to do it manually? D:

Also, does anyone know what it means; standard deviation?

[onur369]

Check attachment.

[Greatness]

I'm not exactly sure but i dont think range/4 is that accurate - im referring to last years exam. Correct me if im wrong.

[ech_93]

thanks guys!