Maths, Addmaths and Statistics: Post your doubts here!

[kitecrystal]

u should know the properties of circle very well, if D and E are tangents to the circle then it is obvious that CD = CE
and DC = 5 cm so EC becomes 5 as well.
the property is that two tangents coming from a single point outside the circle will be equal, here two tangents were coming from C so CE and CD are equal

Sin CAD = 5/13
so CAD = 22.6

thanku i was stuck at the point coz of wrong answer in my redspot..

 

[MustafaMotani]

thanku i was stuck at the point coz of wrong answer in my redspot..

no problem..

 

[MustafaMotani]

yup u are right.. It would be a great help if u tell me the method.. Thank u..

see we have subtract height of triangle from the radius of the circle, see the picture and you will find out why.
to find heigh of triangle I divided the the triangle from O. angle will be halved, from 140 to 70
now apply Cos
COS 70 = h/9
h = cos70 x 9
thus subtract this figure from radius that is 9.
If u dont get it pls dont hesitate to ask again ..

 

[MustafaMotani]

135 ?

yuP...

 

[bogus]

does a cumulative frequency curve always have to touch the x axis????

 

[syed1995]

does a cumulative frequency curve always have to touch the x axis????

No. Not necessarily, but in most cases it does touch it as mostly values start from zero. I haven't yet come across a cumulative curve in our course which hasn't touched the x-axis.

 

[bogus]

No. Not necessarily, but in most cases it does touch it as mostly values start from zero. I haven't yet come across a cumulative curve in our course which hasn't touched the x-axis.

k.... thanks! and can u post a question on sets where we have to find the max or min number of elements in a set?

 

[Haris Bin Zahid]

does a cumulative frequency curve always have to touch the x axis????

Of course it does. The frequencies always start from zero. That's obvious.

 

[bogus]

is standard deviation in r syllabus ??? Haris Bin Zahid ?

 

[Haris Bin Zahid]

is standard deviation in r syllabus ??? Haris Bin Zahid ?

No it's not.

 

[Haris Bin Zahid]

bogus: I have a few mathematical formulas which u can use for checking ur answers of quartiles, median and percentiles. You can get accurate values by them.
Here they are:

1st quartile: l + h/f [(n/4) - C]
3rd quartile: l + h/f [(3n/4) - C]
Median: l + h/f [(n/2) - C]
Percentile: l + h/f [(m*n/4) - C]

l=lower class boundary of the class containing the Q1 or median or Q3 or the mth percentile.
h=width of the class containing the Q1 or median or Q3 or mth percentile
f= frequency of the class containing Q1 or median or Q3 or mth percentile
n=total number of frequencies
C= cumulative frequency of the class immediately preceding to the class containing Q1 or median or Q3 or mth percentile
m=the percentile to be calculated (e.g. 10th percentile, 95th percentile etc)

If u don't understand, I can elaborate in by giving an example. Tell me if u do want!

 

[Phyecomath]

can you help me on D maths oct/nov 2007 paper2 Q8(iv). I tried it and got really confused. help me please

 

[A star]

link please

 

[syed1995]

k.... thanks! and can u post a question on sets where we have to find the max or min number of elements in a set?

Please! if you find any on those sets min max! do share with me .. I have no idea how to solve them!

 

[A star]

can you help me on D maths oct/nov 2007 paper2 Q8(iv). I tried it and got really confused. help me please

8d?

 

[A star]

bogus: I have a few mathematical formulas which u can use for checking ur answers of quartiles, median and percentiles. You can get accurate values by them.
Here they are:

1st quartile: l + h/f [(n/4) - C]
3rd quartile: l + h/f [(3n/4) - C]
Median: l + h/f [(n/2) - C]
Percentile: l + h/f [(m*n/4) - C]

l=lower class boundary of the class containing the Q1 or median or Q3 or the mth percentile.
h=width of the class containing the Q1 or median or Q3 or mth percentile
f= frequency of the class containing Q1 or median or Q3 or mth percentile
n=total number of frequencies
C= cumulative frequency of the class immediately preceding to the class containing Q1 or median or Q3 or mth percentile
m=the percentile to be calculated (e.g. 10th percentile, 95th percentile etc)

If u don't understand, I can elaborate in by giving an example. Tell me if u do want!

i do it in two steps . is it ok? other then by this formulae.

 

[Haris Bin Zahid]

i do it in two steps . is it ok? other then by this formulae.

Didn't understand what u said. Plz elaborate.

 

[Haris Bin Zahid]

i do it in two steps . is it ok? other then by this formulae.

Remember...these formulas are only for checking your answer and for accuracy. You should necessarily plot the lines on the graph.

 

[A star]

Didn't understand what u said. Plz elaborate.

um to find lower quartile range find median of the cumulatve frequency then half it . then find the corresponding range or value on the graph

 

[Haris Bin Zahid]

um to find lower quartile range find median of the cumulatve frequency then half it . then find the corresponding range or value on the graph

Nah.....the graph is a curve and it's not necessary that Q1 is exactly half of the median.
For example the total frequency is 100, the median would be the 50th value. By halving it, the Q1 would be the 25th value. So for finding Q1......you can plot lines on the graph and check the corresponding value on the x-axis.
Is this what u mean to say?
If yes, then that's right.