Author Topic: Urgent: Maths CIE Stats  (Read 13785 times)

Offline $H00t!N& $t@r

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Re: Urgent: Maths CIE Stats
« Reply #45 on: November 01, 2010, 10:02:30 pm »
sorry guys i have another question..  :-[

Eggs produced at a farm are packaged in boxes of six. Assume that, for any egg, the probability that it is broken when it reaches the retail outlet is 0.1 , independent of all other eggs. A box is said to be bad if it contains at least two broken eggs. Calculate the probability that a randomly selected box is bad.

Ten boxes are chosen at random. Find the probability that just two of these boxes are bad.

It is known that, in fact, breakages are more likely to occur after the eggs have been packed into boxes, and while they are being transported to the retail outlet. Explain why this fact is likely to invalidate the calculation.
"If A equals success, then the formula is:
A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

Offline $H00t!N& $t@r

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Re: Urgent: Maths CIE Stats
« Reply #46 on: November 01, 2010, 10:34:53 pm »
the answer is as follows:

0.114; 0.2223   
leave the last part of the question... i understand the answer now
"If A equals success, then the formula is:
A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

Offline $H00t!N& $t@r

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Re: Urgent: Maths CIE Stats
« Reply #47 on: November 01, 2010, 10:38:20 pm »
Give me 10 minutes, i will explain.
alrite thank you!  ;D
"If A equals success, then the formula is:
A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

Offline lana

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Re: Urgent: Maths CIE Stats
« Reply #48 on: November 01, 2010, 10:41:14 pm »
sorry guys i have another question..  :-[

Eggs produced at a farm are packaged in boxes of six. Assume that, for any egg, the probability that it is broken when it reaches the retail outlet is 0.1 , independent of all other eggs. A box is said to be bad if it contains at least two broken eggs. Calculate the probability that a randomly selected box is bad.

Ten boxes are chosen at random. Find the probability that just two of these boxes are bad.

It is known that, in fact, breakages are more likely to occur after the eggs have been packed into boxes, and while they are being transported to the retail outlet. Explain why this fact is likely to invalidate the calculation.

(i) at least two eggs broken: so we find the probability that less than two eggs and then subtract it from one :
(6C1) (0.1)^1 (0.9)^5 + (6C0)(0.1)^0 (0.9)^6 = 0.8857
1- 0.8857=0.144

(ii) from the ten boxes they want the probability of two boxes :
(10C2) ( 0.144)^2 (0.8857)^8 = 0.223

(iii) the event that eggs are broken is not independent of the event that any other egg is broken ( not sure )

i hope it's right because I'm not really sure !!! hope it helps =]
« Last Edit: November 01, 2010, 10:46:48 pm by lana »
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Re: Urgent: Maths CIE Stats
« Reply #49 on: November 01, 2010, 10:46:25 pm »
+rep

Offline $H00t!N& $t@r

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Re: Urgent: Maths CIE Stats
« Reply #50 on: November 01, 2010, 10:53:07 pm »
(i) at least two eggs broken: so we find the probability that less than two eggs and then subtract it from one :
(6C1) (0.1)^1 (0.9)^5 + (6C0)(0.1)^0 (0.9)^6 = 0.8857
1- 0.8857=0.144

(ii) from the ten boxes they want the probability of two boxes :
(10C2) ( 0.144)^2 (0.8857)^8 = 0.223

(iii) the event that eggs are broken is not independent of the event that any other egg is broken ( not sure )

i hope it's right because I'm not really sure !!! hope it helps =]


Thanks a lot again!! +rep again  :D
"If A equals success, then the formula is:
A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

Offline lana

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Re: Urgent: Maths CIE Stats
« Reply #51 on: November 01, 2010, 10:57:07 pm »
your sooo welcome I'm just happy to help   ;)
thank youu guys for +rep   :D
« Last Edit: November 01, 2010, 11:00:26 pm by lana »
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Offline Deadly_king

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Re: Urgent: Maths CIE Stats
« Reply #52 on: November 02, 2010, 04:46:56 am »
Explained it in a easier way

~Sf staff at your service

I like that ;)

Offline TJ-56

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Re: Urgent: Maths CIE Stats
« Reply #53 on: November 02, 2010, 02:58:35 pm »
Can some1 help!?
may/june 2010 paper 61 q5 (ii)
Please explain, the mark scheme is useless on this one
thanx in advance

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Re: Urgent: Maths CIE Stats
« Reply #54 on: November 02, 2010, 03:07:00 pm »
Can some1 help!?
may/june 2010 paper 61 q5 (ii)
Please explain, the mark scheme is useless on this one
thanx in advance


Read the attached Examiners Report for help.


Offline lana

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Re: Urgent: Maths CIE Stats
« Reply #55 on: November 04, 2010, 09:34:01 am »
soo how did you guys do ??  I sat for 62 and I thought it was very tricky  :(
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Offline Deadly_king

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Re: Urgent: Maths CIE Stats
« Reply #56 on: November 04, 2010, 03:12:40 pm »
soo how did you guys do ??  I sat for 62 and I thought it was very tricky  :(

Yeah.......i sat for the same paper as well.

I made some monstrous mistakes that I can't help imagine how i managed to do that >:( :(

It sure was tricky :-\

Offline lana

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Re: Urgent: Maths CIE Stats
« Reply #57 on: November 04, 2010, 03:34:43 pm »
Yeah.......i sat for the same paper as well.

I made some monstrous mistakes that I can't help imagine how i managed to do that >:( :(

It sure was tricky :-\
I DID THE SAME THING  >:(
can you believe that anyone could get the approximation question wrong i  did !!! i forgot to put .5 thing  :( :(
what did you get for the second question the standard deviation, mean and the ?(x-50) and
?(x-50)^2 ??
« Last Edit: November 04, 2010, 03:37:48 pm by lana »
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Re: Urgent: Maths CIE Stats
« Reply #58 on: November 04, 2010, 03:42:49 pm »
I DID THE SAME THING  >:(
can you believe that anyone could get the approximation question wrong i  did !!! i forgot to put .5 thing  :( :(
what did you get for the second question the standard deviation, mean and the ?(x-50) and
?(x-50)^2 ??

Am not sure about the approximation too >:(

I can't remember the mean but I think i got the summation to be 712.

Tell me your values, i'll see if i remember :-[

Offline lana

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Re: Urgent: Maths CIE Stats
« Reply #59 on: November 04, 2010, 03:48:34 pm »
for the summation of (x-50) i got 24 and for the summation of (x-50)^2 i got the same thing 712 or 715 something like that but i cant remember the exact number !! for the s.d i got 6. something or 7.something and for the new mean i got 52.7 !!
and how about the last question (iii) ?? i got 9030 and I'm pretty sure it's wrong !! :-[
« Last Edit: November 04, 2010, 04:12:49 pm by lana »
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