Statistics S1 post your doubts here

[Talha Irfan]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q5 (i) Isn't 12g within the mean supposed to mean that it is 6g above and 6g below the mean?

no, it means it is mean - 12g to mean + 12g

 

[trolololama]

do we study coding?

 

[Talha Irfan]

do we study coding?

no

 

[Haya Ahmed]

no, it means it is mean - 12g to mean + 12g

then why in question 5 here
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_61.pdf

It says withing the mean so we added 12 to the mean and then we did the normal method ?!

 

[Talha Irfan]

then why in question 5 here
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf

It says withing the mean so we added 12 to the mean and then we did the normal method ?!

The questions means that there are equal deviations of 12 g on both sides of the mean so, we can implicitly conclude that the probabilities are equally deviated about the mean so we can say that probability mean - 12 < X < mean + 12 = 0.94 => P(X<mean + 12) = 0.94/2 + 0.5 (the remaining left half of the curve). Now we can use the normal distribution method. Thus, the original definition remains the same.

 

[Evil Philanthropist]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_62.pdf
Question no 5 (iii) Can you please explain how you do the steps to find exclusive?
And 6 (i)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_63.pdf
Question no 3 (iii)

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w10_qp_63.pdf

Question 7- from (ii) till the end.

 

[IGCSE13]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_62.pdf
Question no 5 (iii) Can you please explain how you do the steps to find exclusive?
And 6 (i)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_63.pdf
Question no 3 (iii)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_63.pdf

Question 7- from (ii) till the end.

Q3 iii
Variance = npq , where n is the number of trials p is the probability of success and q is the probability of failure
In this case the number of days is the number of trials hence n=30 and p=0.6 and q=0.4 , var=7.2

 

[Haya Ahmed]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
Q6 (iv) why do we use 50.5 , 125.5 and so on as mid values ?! .. why did we add the 0.5 and from where It Came !?

Q7 fully

Talha Irfan
ZaqZainab

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_62.pdf
Question no 5 (iii) Can you please explain how you do the steps to find exclusive?
And 6 (i)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s10_qp_63.pdf
Question no 3 (iii)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_63.pdf

Question 7- from (ii) till the end.

iii) Mutually exclusive events are those which do not contain any shared events i.e nothing common between the two.
If you look closely, the product of two numbers can not be 24 (Event Q) if both the numbers are greater than 8 (Event R). Hence, they are exclusive!

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
Q6 (iv) why do we use 50.5 , 125.5 and so on as mid values ?! .. why did we add the 0.5 and from where It Came !?

Q7 fully

Talha Irfan
ZaqZainab

Q7
atleast one 3 means it can be one 3 two 3 or more
so easiest this to do it find NO threes
1-no 3's
1-(5/6)^9
ii) n times and so
this time the probability will be
1-(5/6)^n and it should be more than 0.9
make n the subject

 

[Haya Ahmed]

Q7
atleast one 3 means it can be one 3 two 3 or more
so easiest this to do it find NO threes
1-no 3's
1-(5/6)^9
ii) n times and so
this time the probability will be
1-(5/6)^n and it should be more than 0.9
make n the subject

what about Q7 B

 

[Talha Irfan]

what about Q7 B

someone else has replied on the other thread

 

[safa adil]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_62.pdf
Q4 please anyone????

 

[Talha Irfan]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_62.pdf
Q4 please anyone????

i) P of a number being less than or equal to four = 4/9
X - Bin(5,4/9)
P(X>=2) = 1 - [ P(X=0) + P(X=1)]
By solving this binomial expression, you will get the answer 0.735

ii) less than or equal to 4 had probability of 4/9
less than or equal to 3 will have probability of 3/9
so less than or equal to k will have a probability of k/9 . Agreed?

so again X - Bin(n, k/9)

Mean = np => n * k/9 = 96
Variance = npq => n * (k/9) * (1 - k/9) => n * (k/9) * ((9-k)/9) = 32

solve both the equations simultaneously preferably with the equation division method

 

[abdul moeed rana]

stats guess paper for 2014???anyone?

 

[IGCSE13]

thanks alot
can you please help me with mean questions
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_63.pdf Q6 (iii)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_63.pdf Q3 (iii)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf Q6 (iv)

In these above listed questions for finding mean we make intervals. So can you please tell how to make intervals in these questions.
of (weight
Mark and no of pupils )
If you have done these questions can you PLEASE take the pictures and upload them.

If it is <=100 <=150 <=200 then the interval is from 0-100 100-150 150-200 but if it is < only then there are two methods for example if it is <10 <20 <35 then you can either have the interval as 0-10 10-20 ... or you can use the second method which the actual method 0-9 10-19 and so on but you need to further calculate the class boundaries in this case _0.5-9.5 9.5-19.5
I recommend you use the second method because if it is <10 then 10 is not included in the first interval although the final answer will only differ by 1 or 2 dps and from what I have been told since in these questions they are asking for estimates that difference does not matter . I believe you will have confusion between May June 2013 and May June 2011 since these are similar cases but in the marking scheme the methods are different but as I said it does not matter much

 

[ZaqZainab]

If it is <=100 <=150 <=200 then the interval is from 0-100 100-150 150-200 but if it is < only then there are two methods for example if it is <10 <20 <35 then you can either have the interval as 0-10 10-20 ... or you can use the second method which the actual method 0-9 10-19 and so on but you need to further calculate the class boundaries in this case _0.5-9.5 9.5-19.5
I recommend you use the second method because if it is <10 then 10 is not included in the first interval although the final answer will only differ by 1 or 2 dps and from what I have been told since in these questions they are asking for estimates that difference does not matter . I believe you will have confusion between May June 2013 and May June 2011 since these are similar cases but in the marking scheme the methods are different but as I said it does not matter much

I was really confused about this question and i did the same way as you did
but i finally got it The number of students can not be 0 if students are 0 there is no school so it is 1-100 101-150 ........

 

[IGCSE13]

I was really confused about this question and i did the same way as you did
but i finally got it The number of students can not be 0 if students are 0 there is no school so it is 1-100 101-150 ........

thank you so much I was just about to correct myself

 

[safa adil]

i) P of a number being less than or equal to four = 4/9
X - Bin(5,4/9)
P(X>=2) = 1 - [ P(X=0) + P(X=1)]
By solving this binomial expression, you will get the answer 0.735

ii) less than or equal to 4 had probability of 4/9
less than or equal to 3 will have probability of 3/9
so less than or equal to k will have a probability of k/9 . Agreed?

so again X - Bin(n, k/9)

Mean = np => n * k/9 = 96
Variance = npq => n * (k/9) * (1 - k/9) => n * (k/9) * ((9-k)/9) = 32

solve both the equations simultaneously preferably with the equation division method

thank you so mush talha

 

[Talha Irfan]

thank you so much Talha

you're welcome safa