A level Statistics doubt??Post your doubts here!

[syed1995]

P(z>a)=0.888
P(z<-a)=0.888
Phi(-a)=0.888
1-Phi(a)=0.888
Phi(a)=0.112
a=invPhi(0.112)
a=-invPhi(1-0.112)
a=-invPhi(0.888)

and the second one ..

(z<t)=0.25
Phi(t)=0.25
t=invPhi(0.25)
t=-invPhi(1-0.25)
t=-invPhi(0.75)

kiara15

Did ya get the working?

 

[PhyZac]

i dont get it y am i not getting notifs from this thread???

Below log out, there is in a red colour written "Watch thread"
Click that.

 

[syed1995]

thanks but i didnt understood when we have to take constant neg and when positive n then inverse concept etc?

Just remember this..

P(x>t) = P(x<-t)
= 1-Phi(t)

And

P(x>-t) = P(x<t)
= Phi(t)

While on the right hand side if inverse of Phi is less than 0.5 (NOT ON TABLE)..

Then invPhi(0.25) = -invPhi(1-0.25) = -invPhi(0.75)

 

[iFuz]

Explain?

 

[syed1995]

Explain?

What?

 

[panoramafolks]

its a good question
one should solve this

A fair five-sided spinner has sides numbered 1, 2, 3, 4, 5. Raj spins the spinner and throws two fair
dice. He calculates his score as follows.
• If the spinner lands on an even-numbered side, Raj multiplies the two numbers showing on
the dice to get his score.
• If the spinner lands on an odd-numbered side, Raj adds the numbers showing on the dice to
get his score.
Given that Raj’s score is 12, find the probability that the spinner landed on an even-numbered side.

p ( even number and score 12) = ((2/5)*(1/9)) = 2/45
p(odd and 12) = (3/5) * (1/36) = 1/108
p(12 as score) = 29/540

p(even|12) = (2/45) / (29/540) = 24/29 .

plz tell me if i am corect.

 

[shafayat]

c'mon .. third time I am posting :/ this
please help me with the probability part

 

[Anika Raisa]

c'mon .. third time I am posting :/ this
please help me with the probability part

 

[kiara15]

syed1995
yeah finally understood, working and concept too thaaanku,,

 

[kiara15]

like in (z<t)=0.25, 0.25 is less than 0.5 so it wil be -fi[1-0.25] and again fi[1-0.75]



right?

can u write general rules of such type of equations plzz?

 

[x-gamer-x]

p ( even number and score 12) = ((2/5)*(1/9)) = 2/45
p(odd and 12) = (3/5) * (1/36) = 1/108
p(12 as score) = 29/540

p(even|12) = (2/45) / (29/540) = 24/29 .

plz tell me if i am corect.

p(odd and 12) = 1/60 not 1/108

 

[daredevil]

View attachment 26525

HI man ..
I am sorry I am not real neat with my work ..
but how I like to do these questions is by making a two way table like in the image ..
draw the table as first dice and second dice ... then inside write only what question says ! like its the lower value of the two numbers .. and also if its the same number on both dice then he writes the number on one of the dices .. sooo u just complete the table like 1,1 the answers are same so the result he wud write is 1 ,,, den 1,2 the lower result is two ! so like that we fill the table ..
then to write the probabilities we just count the number of 1'ns in the table and divide by the total number of solutions that is 36 here ! ( the total number of answers u got IN the table ) then we count 2's and write .. same way for others !!

the table wud be
11/36 , 9/36 , 7/36 , 5/36 , 3/36 , 1/36

,
.
please correct me if I am wrong .. hope I cud help

easy way to solve these type of question draw a probability distribution table . it will show you all 36 probabilities then all you have to do is copy and write down

thankkkss

 

[syed1995]

like in (z<t)=0.25, 0.25 is less than 0.5 so it wil be -fi[1-0.25] and again fi[1-0.75]



right?

can u write general rules of such type of equations plzz?

YEAH... -fi(0.75) = fi(0.25) you got that right...

(z<t)=0.25
Phi(t)=0.25
t=invPhi(0.25)
t=-invPhi(0.75) Answer

 

[Champ101]

Fahad has 4 different coloured pairs of shoes (white, red, blue and black), 3 different coloured pairs of jeans (blue, black and brown) and 7 different coloured tee shirts (red, orange, yellow, blue, green, white and purple).
How many different ways can Fahad arrange his 3 jeans and 7 tee shirts in a row if the two blue items are not next to each other?

I got 10!/2! - 9! , but its wrong. :/ someone please explain me this.

 

[syed1995]

Fahad has 4 different coloured pairs of shoes (white, red, blue and black), 3 different coloured pairs of jeans (blue, black and brown) and 7 different coloured tee shirts (red, orange, yellow, blue, green, white and purple).
How many different ways can Fahad arrange his 3 jeans and 7 tee shirts in a row if the two blue items are not next to each other?

I got 10!/2! - 9! , but its wrong. :/ someone please explain me this.

that'd be wrong.. dividing by 2! since there is no repetition..

To solve this Find Together and subtract from total...

BT BJ _ _ _ _ _ _ _ _

Total - Together
10! - (2!*8!*9)
=2903040

That the correct answer?

 

[shafayat]

thankkkss

no Problem

 

[shafayat]

thanks a lot man!
I seriously thank you (Y) .. and the probability part is soo dayum hard no one could get it correct at the first try

 

[A star]

well guys after three days of hardwork i have come to the conclusion . stats is HARD -___-

 

[syed1995]

http://papers.xtremepapers.com/CIE/...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).

 

[syed1995]

well guys after three days of hardwork i have come to the conclusion . stats is HARD -___-

wow you worked hard to come to that conclusion? I could have told you that before and you wouldn't have wasted 3 days...