Mathematics: Post your doubts here!

[Wanzi21]

and this? sory if I keep asking haha..
well just want to know how to do the 5(i)..

 

[Khan_971]

man ure a robot i guess

Nah. Im freaked out. p4 and p6. This is one pressure week

 

[Khan_971]

View attachment 10562

and this? sory if I keep asking haha..
well just want to know how to do the 5(i)..

I love these questions. They are the easiest, that's why.

Within 12 g implies the least is 20-12 = 8 and highest = 20+12 =32
so P(8<X<32)
P( 8-20 / σ <Z< 32-20 / σ)
P(-12/σ <Z < 12/σ)
Seems familiar?

 

[mominzahid]

that wierd symbol. ϕ is the fi. the function through which u have to go to the table

Ahh... thankss..
will get back to u with more problems..
are u a teacher or a student?

 

[Khan_971]

Ahh... thankss..
will get back to u with more problems..
are u a teacher or a student?

Well that's a surprising question. Student, though.

 

[Richmondtan]

Hye guys,i have a question,I have came across some histograms and i have no idea which one is a correct one. Why some histograms their class boundary are in decimals(0.5) while some are in round numbers? I mean when you draw it,some draw from the 0.5 while some draw on round numbers?

 

[GoodRobot]

you're looking for a number 'n', where 5000 < n < 6000 [or more precisely, the smallest and the largest number you can possibly achieve is 5123 and 5643 respectively] .. can't ever start with 6, can it?

thanks

 

[Khan_971]

Hye guys,i have a question,I have came across some histograms and i have no idea which one is a correct one. Why some histograms their class boundary are in decimals(0.5) while some are in round numbers? I mean when you draw it,some draw from the 0.5 while some draw on round numbers?

Well. It depends on the intervals in the group data. If an Upper Boundary of the Interval is the same value as the Lower Boundary of the next interval, then there's no need to add/subtract .5 to the corresponding boundaries. I.e,
0-100, 100-200

But if it is 1-99, 100-149. Then subtract .5 from Lower boundary and add .5 to the upper.
.5-99.5, 99.5-149.5.
There Simply cannot be empty space WITHIN a histogram unless an interval has frequency of 0

 

[GoodRobot]

im not able to solve Q2...help !
http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_61.pdf
and also i hv seen similar questions in many years recently,can some one tell me how to go about it ?

 

[Wanzi21]

I love these questions. They are the easiest, that's why.

Within 12 g implies the least is 20-12 = 8 and highest = 20+12 =32
so P(8<X<32)
P( 8-20 / σ <Z< 32-20 / σ)
P(-12/σ <Z < 12/σ)
Seems familiar?

then its probability is 0.94?

 

[mukki]

Hye guys,i have a question,I have came across some histograms and i have no idea which one is a correct one. Why some histograms their class boundary are in decimals(0.5) while some are in round numbers? I mean when you draw it,some draw from the 0.5 while some draw on round numbers?

its like where you have continuous boundaries like 0<t<20,20<t<40 and so on then u dont have subtract .5 but if the boundaries are like 10<t<30 , 31<t<40 then ul have to subtract .5 and make it like 9.5<t<30.5 ,30.5<t<40.5 and so on

 

[Khan_971]

then its probability is 0.94?

yes.

 

[Khan_971]

im not able to solve Q2...help !
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
and also i hv seen similar questions in many years recently,can some one tell me how to go about it ?

Mean= Σ(x − a)/n +a
where a is a constant

Variance Σ(x − 25)^2 / n - [mean]^2

 

[mominzahid]

Well that's a surprising question. Student, though.

Hahah... just figured u know so much there's a good chance u might be a teacher..

 

[mukki]

im not able to solve Q2...help !
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
and also i hv seen similar questions in many years recently,can some one tell me how to go about it ?

alright here you go
i)When ever you have to find the original mean=E(x-a)/n +a
so here the mean is given as 28.325. Find the value of n from the equation by substituting the value of E(x-a). 28.325-a=E(x-a)/n where a=25 n=40
For the s.d you should remember that s.d isnt affected by constant shifts in the data such as -a.
assume that x-a =y so E(x-a)=E and hence E(x-a)^2=E^2
s.d=underoot(E^2/n-(E/n)^2)
s.d=9.11
ii)check your data booklet one of the formula for s.d is underoot(E(x)^2/n - (E(x)/n)^2). Since you know that the s.d is 9.11 and that the original mean is 28.325 substitute the given values and find the value of (E(x)/n )^2.

 

[GoodRobot]

Mean= Σ(x − a)/n +a
where a is a constant

Variance Σ(x − 25)^2 / n - [mean]^2

is there any book or site where i can get the concept of this formula ? thanks,by the way

 

[Wanzi21]

yes.

i didnt get it right... in MS how in the world did they get Z=1.882..
I checked on the normal dis. table already..

 

[mukki]

I used the alphabet y which is in brackets ()where u see the thumbs up icon

 

[mominzahid]

Well that's a surprising question. Student, though.

hey check this question out.. in part 2 u do 4!/2! right? how to solve part 1 using this factorial method? it gets me confused when to use the factorials and when to use nPr.. :/

 

[Khan_971]

is there any book or site where i can get the concept of this formula ? thanks,by the way

I am not so sure, :/ do u Live in Khobar/Dammam?