A level Statistics doubt??Post your doubts here!

[Ryan123]

M/J/07 Q3
plz also do part b

well P(X>5.2)=.9 since probability is greater then .5 we have to assume that mean is greater than 5.2 so it becomesP(Z>5.2-2sd/sd)=.9 so P(Z<5.2-2sd/sd)=.9 and then you get 5.2-2sd=1.282sd and then do the calculation for sd which is 7.24
f
for 2nd part
(mean-s.d<X<mean+s.d) soP(mean-sd-mean/sd<Z<mean+s.d-mean<s.d)....P(-1<Z<1) then solve it with 2P(Z<1)-1=.686...then multiply .686and800 to get the ans

 

[Anika Raisa]

Check on the left side!

thanks but no math tab in http://studyguide.pk/

 

[kiara15]

Check on the left side!

thaaank u god bless and i had 1 more ques and when we assume unknnown value normal distriution chap how we geet to knw that value is postiv or neg/?
e.g let p(Z>a) = 0.25 and t is positive, hw do we knw that? and are we suppose to attempt p,paprz after 2010 or before these years too?

 

[x-gamer-x]

well P(X>5.2)=.9 since probability is greater then .5 we have to assume that mean is greater than 5.2 so it becomesP(Z>5.2-2sd/sd)=.9 so P(Z<5.2-2sd/sd)=.9 and then you get 5.2-2sd=1.282sd and then do the calculation for sd which is 7.24
f
for 2nd part
(mean-s.d<X<mean+s.d) soP(mean-sd-mean/sd<Z<mean+s.d-mean<s.d)....P(-1<Z<1) then solve it with 2P(Z<1)-1=.686...then multiply .686and800 to get the ans

thanks bro
but for (i) we have to consider negative sign with 1.282sd else we will get wrong answer i.e. .828
i just want to know y we have to use negative sign with 1.282sd

 

[Anika Raisa]

thaaank u god bless and i had 1 more ques and when we assume unknnown value normal distriution chap how we geet to knw that value is postiv or neg/?
e.g let p(Z>a) = 0.25 and t is positive, hw do we knw that? and are we suppose to attempt p,paprz after 2010 or before these years too?

umm c here... http://people.richland.edu/james/lecture/m170/ch07-bin.html

Also only when p(Z<a) then usually the prob is +ve n when P(Z>a) u take neg
P(Z>a)=1-P(Z<a)

Its better to do pprs from 2007 onwards....

Its nt possible now so just pick up sums u hv difficulty wid n do em...

 

[Ryan123]

thanks bro
but for (i) we have to consider negative sign with 1.282sd else we will get wrong answer i.e. .828
i just want to know y we have to use negative sign with 1.282sd

hmm you have to understand the bell diagram
Look at like this if value of z is a(which is not negative) then P(Z<a) has to be greater or equals to 0.5 and P(Z>a) has to be less/equals to 0.5
now if a is negative then P(Z<a) will be less than 0.5 and P(Z>a) will be greater than 0.5 and thats how you understand it

 

[x-gamer-x]

hmm you have to understand the bell diagram
Look at like this if value of z is a(which is not negative) then P(Z<a) has to be greater or equals to 0.5 and P(Z>a) has to be less/equals to 0.5
now if a is negative then P(Z<a) will be less than 0.5 and P(Z>a) will be greater than 0.5 and thats how you understand it

thank u so much bro
may god bless u and u get all A's and A*s
and remember me in ur prayers as well

 

[Anika Raisa]

Alice123 ON11/61 no.7

C here they say exactly two not at least so u cnt have three same no.

Nw lets list d possible outcomes,
They are....

1. 8 from A n 8 from B n anything except 8 from C
2. 8 from A n 8 from C n anything xcpt 8 from B
3. 2 from A n 2 from C but any other from B
4. 8 from B n 8 from C but any other from A

So now lets calculate probability

1. 1/4*2/5*3C1.... (Cz u c u hv 3 other no.s xcept 8 in C)
2. 1/4*3C1*4/7
3. 1/4*5C1*1/7
4. 3C1*2/5*4/7

Now add the results of 1 2 3 n 4 ! U hv ur ans!!

Hope i cud help! Sorry ma copy is too messy 4 me even so i tht writing it out ws btr n sorry 4 being l8! u knw usual net drama!! !

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf
Q7a please Anika Raisa Do u have this done?

 

[Alice123]

Alice123 ON11/61 no.7

C here they say exactly two not at least so u cnt have three same no.

Nw lets list d possible outcomes,
They are....

1. 8 from A n 8 from B n anything except 8 from C
2. 8 from A n 8 from C n anything xcpt 8 from B
3. 2 from A n 2 from C but any other from B
4. 8 from B n 8 from C but any other from A

So now lets calculate probability

1. 1/4*2/5*3C1.... (Cz u c u hv 3 other no.s xcept 8 in C)
2. 1/4*3C1*4/7
3. 1/4*5C1*1/7
4. 3C1*2/5*4/7

Now add the results of 1 2 3 n 4 ! U hv ur ans!!

Hope i cud help! Sorry ma copy is too messy 4 me even so i tht writing it out ws btr n sorry 4 being l8! u knw usual net drama!! !

thanku soooo much...u're nt late at all

 

[Anika Raisa]

thanku soooo much...u're nt late at all

uff i tht i ws gettin u impatient!! Well hope i was clear enouh!!! N it was ma pleasure! thanks to u actuali cz i had an revision!!!

 

[Alice123]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s11_qp_61.pdf
q3iii

 

[A star]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_61.pdf Q1

 

[Alice123]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_61.pdf Q1

in your words , "apply continuety corrective"

 

[A star]

in your words , "apply continuety corrective"

i want the working done einstien

 

[x-gamer-x]

plz someone do this

The volume of milk in millilitres in cartons is normally distributed with mean µ and standard deviation
8. Measurements were taken of the volume in 900 of these cartons and it was found that 225 of them
contained more than 1002 millilitres. Calculate the value of µ.

 

[kiara15]

umm c here... http://people.richland.edu/james/lecture/m170/ch07-bin.html

Also only when p(Z<a) then usually the prob is +ve n when P(Z>a) u take neg
P(Z>a)=1-P(Z<a)

Its better to do pprs from 2007 onwards....

Its nt possible now so just pick up sums u hv difficulty wid n do em...

umm ok thaanks for help. god bless u with a*s ameen

 

[salvatore]

salvatore
Sorry 4 the l8 reply though

View attachment 27152

Hope i cud be helpful!
Notes on Prob distribution:

Thank you so much!

 

[A star]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_61.pdf Q5 part ii why havent they subtracted one from final answer MustafaMotani

 

[Alice123]

i want the working done einstien

n=250
p =0.86
np=250*0.86=215>5
nq=259*0.14=35>5
mean=250*0.86=215
var=npq=30.1
X is a normal distribution of(215, 30.1)
P(X>210)
so applying continuity corrections,
P(Z>210.5-215/root(30.1))
=P(Z>-0.8202)
=0.794

 

[kiara15]

how to take inverse fi?