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Statistics S1 post your doubts here

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http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_62.pdf

can anyone plz help me with ques 2, the distribution table i suck in maths and i don't know this :(
The random variable Y takes the value 0 if thetwo values of X are the same. Otherwise the value of Y is the larger value of X minus the smaller value of X
So it is 2 and 2 or 4 and 4 or 6 and 6
then y=0
now to make the table we know 0 is there for sure
then use the other information
if 2 and 4
then y=4-2 (bigger value - smaller value)
or it can be 6 and 2 there y=6-2=4
ALL the possible ways of getting y=0
2 and 2 -------> from the table above (o.5*0.5)
4 and 4 ------>(0.4*0.4)
6 and 6 ------->(0.1*0.1)
add all this up you will get 21/50

ALL the possible ways you can get y=2
2 and 4 -----> (0.5*0.4)
4 and 2 ------>(0.4*0.5)
6 and 4 ------>(0.1*0.4)
4 and 6 ------>(0.4*0.1)
add all this up you get 12/25

ALL the possible ways of getting y=4
6 and 2 ------->(0.1*0.5)
2 and 6--------->(0.5*0.1)
add this up and you get 2/20

now making the table y 0 2 4
p(Y=y) 21/50 12/25 2/20
 
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they asked 8% of carrots are shorter than c cm. Find the value of c. so why they subtracted 0.08-1 ? can u explain please
p(x<c)= 0.08
p(z<((c-14.2)/3.6)=0.08
ϕ((c-14.2)/3.6)=0.08
BUT if you see the table you cant find 0.08 and so you have to do 0.08-1
and then the z value you get from 0.08-1 you will add a negative sigh to it
You know you are having an exam in less than 10 hours you should know this my dear
 
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p(x<c)= 0.08
p(z<((c-14.2)/3.6)=0.08
ϕ((c-14.2)/3.6)=0.08
BUT if you see the table you cant find 0.08 and so you have to do 0.08-1
and then the z value you get from 0.08-1 you will add a negative sigh to it
You know you are having an exam in less than 10 hours you should know this my dear
ok thank u so much hope we all get the grades we wish
 
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thank you :)
The random variable Y takes the value 0 if thetwo values of X are the same. Otherwise the value of Y is the larger value of X minus the smaller value of X
So it is 2 and 2 or 4 and 4 or 6 and 6
then y=0
now to make the table we know 0 is there for sure
then use the other information
if 2 and 4
then y=4-2 (bigger value - smaller value)
or it can be 6 and 2 there y=6-2=4
ALL the possible ways of getting y=0
2 and 2 -------> from the table above (o.5*0.5)
4 and 4 ------>(0.4*0.4)
6 and 6 ------->(0.1*0.1)
add all this up you will get 21/50

ALL the possible ways you can get y=2
2 and 4 -----> (0.5*0.4)
4 and 2 ------>(0.4*0.5)
6 and 4 ------>(0.1*0.4)
4 and 6 ------>(0.4*0.1)
add all this up you get 12/25

ALL the possible ways of getting y=4
6 and 2 ------->(0.1*0.5)
2 and 6--------->(0.5*0.1)
add this up and you get 2/20

now making the table y 0 2 4
p(Y=y) 21/50 12/25 2/20
 
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do u have any notes or advise about combination and permutation ?
Permutation (arrangements)
order of objects is important
the number of ways of arranging 'n' unlike objects in a line is n!
the number of 'n' objects if p are alike then number of arrangements=n!/p!
the number of ways of arranging n unlike objects in a circle is (n-1)!
the number of arrangements of 3 objects taken from n unlike objects nPr=n!/(n-r)!
 
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