IGCSE MATHS Doubts

[Vin]

like this one .. =|

[Shazizzzle]

I hate HISTOGRAMS .. !!  somebody any tip for solving them ?? u wan me to post a paper ?? pls anything..

f.d = k X f/c.w

K, the constant.
When, both frequency AND histogram i.e frequency density for one group are given, use them to find K.
Sometimes, the f.d may not be equal to f/c.w.
Once you have, use the formula to either find
1. f.d of groups with F already given, and use it to make the bar...
OR
2. Use the f.d on the histogram given to find th F and record in table.

[Ghost Of Highbury]

w09, paper 4, 2)iv

ok this negative shear factor thingy is horrible..i cant figure it out y the move upwards is considered negative.

anyhow, its always wiser to use the matrix method

take two object and correspoding image co-ordinates..

(-4,1) --> (-4,5)

(-1,1) --> (-1,2)

check the image attached

a shear transformation matrix with y-axis is invariant is = (1  0)
                                                                            (k   1)

here k = -1

[Adzel]

f.d = k X f/c.w

K, the constant.
When, both frequency AND histogram i.e frequency density for one group are given, use them to find K.
Sometimes, the f.d may not be equal to f/c.w.
Once you have, use the formula to either find
1. f.d of groups with F already given, and use it to make the bar...
OR
2. Use the f.d on the histogram given to find th F and record in table.

Can you explain more; like what is k and c.w

[ksitna]

loll hey baladya
i just realised we usually have the same number of posts

[Baladya]

Hey guys i have an imp tip...
If u have a group of data in a table annd u want to find the median, here is the way.
If the total number of data (cumulative frequency) is an even number do this: Calculate n/2. Calculate (n/2)+2. Get the average of them. The average tells the postition of the median(undeer which group).
If its an odd number: Don't remember xD Anyone knows ???
Hope this helped...

[Baladya]

loll hey baladya
i just realised we usually have the same number of posts

NOOO U CHEATED xD   Hahaha Weird

[Ghost Of Highbury]

like this one .. =|

can u give the answers too plz? maybe i can help..

[Shazizzzle]

like this one .. =|

Here, for e.g., 0-10 has 300 patients.

f.d=15 (count squares height)
frequency=300 (given in table)
c.w (class width)= 10 (0-10, the interval width is 10)

f.d = k X f/c.w
15 = K X 300/10
15=K x 30
K=15/30
K=1/2

Now, the area of the bar is 5 X 15 = 75
Frequency is 300
So, frequency for one small block: 300/75 = 4
and, the number of small blocks in 1 cm^2 = 25 (5 X 5)
SO, frequency of 1cm^2= 4 X 25 = 100 patients.

Now, part b.
The height, of f.d is 20.
We need F (i.e no of patients to fill table)
f.d = k X f/cw
20 = 1/2 X f/30
20 = f/60
f= 20 X 60
f=1200

[Vin]

Page 6 q. 13 .. post a q. A@di is always there to ans it !! Thanks ..

[Shazizzzle]

SIMPLE MEDIAN METHOD.

Total number of terms (sum of frequencies) = n

n/2

if the ans to the above is in decimals, e.g say 7.5, the you round it, to the next term. 8. So THE 8TH term is THE MEDIAN.

If the ans to the above is an integer, say 10, you take 10, AND THE NEXT, i.e 10th AND 11th terms, take their average (i.e 10th + 11th / 2)
and, voila, that's the median.

SIMPLE.

[Vin]

@ Shazizzzle .. Thanks .. i'd figured tht out already .. +rep for the efforts ..

u've answered a couple ov answers before too .. Thanks ..

[Baladya]

Page 6 q. 13 .. post a q. A@di is always there to ans it !! Thanks ..

Vin: a) is 20 its because if u take the square next to the origin (1cm3 square) it has a base of 10 years and a hieght of 10 pateints. Just multiply the two as if u want the area of that square

[Shazizzzle]

Umm, June 2007, Q12. Which region is shaded?

[Ghost Of Highbury]

ok shazzizle has already answered.

v use the same formula

first find the standard width (k)

sw = (h*cw)/f

then find the height

h = f * (sw/cw)
@baladaya - a is 100. 300/75 = 4. 25*4 = 100