A-Level Edexcel Statistics S1 January 2008 Q6a,b (Normal Distribution) : ExamSolutions

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[ExamSolutions_Maths]

Yes, I would have thought so but I was using the official tables for Edexcel at the time and these would be the ones that you would use if you did the exam.

[ExamSolutions_Maths]

Cool. Getting late now and I am quitting for the night.

[Lyricsforyou]

Thanks for the videos. They really help

[ddzproduction]

sorry I couldn't finish all of it in that post. Yes you will lose 1 mark because you are supposed to use the table on page 202 which is for p(Z > z) (0.2000 in this case). And the shaded area in this table at page 202 is now represented by 'p' and the corresponding axes by z.

[ExamSolutions_Maths]

@twilighter2k8 This is a defined distribution - take a look at my earlier tutorials on the normal distribution before doing these exam questions for why we use this.

[ddzproduction]

No you are wrong. The 0.80 you are looking at is z from the table, remember the shaded area is equal to 0.8000 not the z value on the axes. So you are looking for the right hand side values on that long table at page 201 in s1 book, there the closest to 0.8000 is 0.7995 and 0.8023, but 0.7995 is even closer to 0.8000 than 0.8023 so therefore in this tut he choose that value and the corresponding z value to that is 0.84 which will give you very close answer but you will lose 1 mark still I think.

[LoveForOreos]

oh, i was using the edexcel formulae list for sept 2009 :S

[tuana]

What i dont get is it says only 60% of the bags weigh between 190g and 210g so the other 40% are outside that range :.How do we know the median is 200g when it may be the upper 60% or lower 60% and not the middle 60%

[LoveForOreos]

I have a table which has the exact value for 0.80, which is 0.7881, so that would mean my sigma came to 12.7g, which is quite far off from 11.9. Would they still allow that?

[marwanawad]

would it make a difference if i used 0.84 not 0.8416 bc in the end they both give me the same rounded answer? if it doesnt matter then why would i lose a mark for not including the 0, .8416?

[dineshn]

i got 11.904...

is this still right? the exam board said something weird about losing mark but only on (a)...didnt understand. Its because my tables gave me 0.84