A level Statistics doubt??Post your doubts here!

[A star]

it should be like this ((19-b-19)/1.5<z<(19.5+b)/1.5)>pphieinverse of (0.8)???
i think sub answer from 1?

 

[Kumkum]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s05_qp_6.pdf

Question 6 Part ii .. How do you calculate z over here? I can do the rest easily.. the value of z which is coming for me is the one where they offer 2/3 marks (for answer and method.. but not for the value of z).

what did u get as ur value for z?

 

[syed1995]

what did u get as ur value for z?

from table 0.842 for 0.8 probability

then 2(b/0.15)-1 = 0.842
2(b/0.15)=1.842
(b/0.15)=0.921

 

[Kumkum]

from table 0.842 for 0.8 probability

then 2(b/0.15)-1 = 0.842
2(b/0.15)=1.842
(b/0.15)=0.921

its actually phi-inverse of 0.9 not 0.8
this is how i did it
the shaded area is 0.8 so u'll have
2phi(z) - 1 = 0.8
phi(z) = 0.9
so z= phi-inverse 0.9
=1.281 its +/- 1.281
then u can use these values to get b which will also be +/- so that u can find 1.9-b and 1.9+b
hope u got it

 

[syed1995]

its actually phi-inverse of 0.9 not 0.8
this is how i did itView attachment 26737
the shaded area is 0.8 so u'll have
2phi(z) - 1 = 0.8
phi(z) = 0.9
so z= phi-inverse 0.9
=1.281 its +/- 1.281
then u can use these values to get b which will also be +/- so that u can find 1.9-b and 1.9+b
hope u got it

ah thanks.. I guess I have started showing signs of stats getting way over my head =,= .. And I should try and study something other than stats Hope I don't do these mistakes in the CIE paper!

 

[Kumkum]

ah thanks.. I guess I have started showing signs of stats getting way over my head =,= .. And I should try and study something other than stats Hope I don't do these mistakes in the CIE paper!

ur welcome
dnt worry it happens...stats is just a problem.....

 

[Dashexdan]

plese someone clear question 2 for me ?
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_62.pdf
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_ms_62.pdf

 

[Z.A.M]

plese someone clear question 2 for me ?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_62.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_ms_62.pdf

if u see Y can only take the values 0 2 or 4 and since 0 would be when its either 2,2 4,4 or 6,6 u multiply the indiviual probabilities of getting a 2 4 and 6 and add them eg 0.5x0.5 +0.4x0.4+0.1x0.1=0.42
likewise u can solve for 2 and 4 i hope u get what i said

 

[Dashexdan]

if u see Y can only take the values 0 2 or 4 and since 0 would be when its either 2,2 4,4 or 6,6 u multiply the indiviual probabilities of getting a 2 4 and 6 and add them eg 0.5x0.5 +0.4x0.4+0.1x0.1=0.42
likewise u can solve for 2 and 4 i hope u get what i said

ok thanx

 

[maulvi]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_61.pdf Can someone tell me how to do question 5 a please ?

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w09_qp_61.pdf Can someone tell me how to do question 5 a please ?

5ai) number has to be 5xxx hence threee places 5 numbers so do 5P3
second part daredevil MustafaMotani guys help please

 

[sufyanalizaib]

salam...am struckd on one part ov the question...
In a random sample of 1000 body feathers from birds of a certain species, how many would the researcher expect to find with lenghts more than 1 standard deviation from the mean??

 

[A star]

salam...am struckd on one part ov the question...
In a random sample of 1000 body feathers from birds of a certain species, how many would the researcher expect to find with lenghts more than 1 standard deviation from the mean??

2/3

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_61.pdf Q6 part ii

 

[MustafaMotani]

5ai) number has to be 5xxx hence threee places 5 numbers so do 5P3
second part daredevil MustafaMotani guys help please

6 x 6 x 6 =216
is it correct.. ?

 

[A star]

6 x 6 x 6 =216
is it correct.. ?

yes but how?

 

[MustafaMotani]

yes but how?

first no. is 5
second third and fourth number has 6 possible numbers

so 6C1 x 6C1 x 6C1

 

[A star]

first no. is 5
second third and fourth number has 6 possible numbers

so 6C1 x 6C1 x 6C1

ahhh i see -_-
thanks mate

 

[sufyanalizaib]

DUde A star i can also access to the MS....but i need an explanation :/

 

[Kangxidi]

salam...am struckd on one part ov the question...
In a random sample of 1000 body feathers from birds of a certain species, how many would the researcher expect to find with lenghts more than 1 standard deviation from the mean??

3alaikumissalam.

Work out the P(X > mean + sd)

I can't remember which year that is, but I will just give you a quick example.

If the question is X~N(10,5^2) (10 mean and 5 sd) and you are looking for lengths MORE THAN 1 sd from the mean, that means you need to work out P(X > 10 +5)

That is P(X>15).

Whatever answer you get, multiply it by 1000.

Hope that helps.