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Edexcel Statistics S1 Exam Jan 2008

muell

Hi,

125, 160, 169, 171, 175, 186, 210, 243, 250, 258, 390, 420
these are the values after sorting them out (I think)

to work out the right term for q1 = (1/4)*12 = 3
3 is an intenger
therefore you take the average value of the third and the fourth term
so 0.5*(169+171)= 170
so q1= 170

I ve used similar methods to work out the other quartiles:
q2= 198
q3= 254

I am not sure if this is correct but that is how i did it :smile:

might be wrong though :p:

I think you might be right.

I did it this way:

Q_1 = \frac{n + 1}{4}

Q_2 = \frac{n + 1}{2}

Q_3 = \frac{3(n + 1)}{4}

^^Which I'm starting to believe is wrong.

Reply 101

M.A.H

17

edward_wells90

Did anyone else did 388.5 for the outliers lower boundary thing?

For the upper quartile, lower quartile and median thing:

Q_1

= 171 /

Q_2

= 210 /

Q_3

= 258

\frac{Q_1 - 2 Q_2 + Q_3}{Q_3 - Q_1}

\frac{171 - 2 (210) + 258}{258 - 171} = 0.103 (3sf)

^^ Did anyone else get this?

I got -5.88 :mad:

stupid calculater

Reply 102

Ar5enal Fan

OP

10

edward_wells90

Did anyone else did 388.5 for the outliers lower boundary thing?

For the upper quartile, lower quartile and median thing:

Q_1

= 171 /

Q_2

= 210 /

Q_3

= 258

\frac{Q_1 - 2 Q_2 + Q_3}{Q_3 - Q_1}

\frac{171 - 2 (210) + 258}{258 - 171} = 0.103 (3sf)

^^ Did anyone else get this?

I think I just took the 6th number as the median :frown:

Reply 103

Alessandro_22

8

i hot an E in maths last year, i've tried so hard and by reading all these posts i know i'm defo not going to get an A, feel like breaking down

thanks lol

Reply 104

Ar5enal Fan

OP

10

gj3

i hot an E in maths last year, i've tried so hard and by reading all these posts i know i'm defo not going to get an A, feel like breaking down

thanks lol

Lol, I got a C last year which was disappointing and I think I've done ok for C1 and S1 this time around, but C2 I didn't do well in and I don't understand C3!! But I only need to get a B for maths as LSE only need AAB for Accounting and Finance and I was predicted A, which I will try to get!

Don't worry just keep working hard and I'm sure by summer you'll be at an A grade when you retake

Reply 105

Alessandro_22

8

i'm predicted a c lol

Reply 106

muell

i think my method (described above somewhere) might be wrong, because this is used to find the quartiles of a frequency distribution and not for a set of data as given in the exam.
I m quiet confused :confused:

Too late to make any changes so dont care anymore :smile:

Reply 107

Ar5enal Fan

OP

10

muell

i think my method (described above somewhere) might be wrong, because this is used to find the quartiles of a frequency distribution and not for a set of data as given in the exam.
I m quiet confused :confused:

Too late to make any changes so dont care anymore :smile:

Lol, that's the spirit! In reflection there were quite a few tricky questions, I came out of the exam hall feeling confident but I think I made some stupid mistakes now :frown:

Reply 108

Alessandro_22

8

i was expecting an A after doing so many pastpapers just this histogram and normal distribution which has done me over, oh well i'm not going to give up, well done to everyone

Reply 109

vinsta

12

60 raw for an A then, or more or less???

Reply 110

username141550

2

Argh! That histogram question has annoyed me now! I put 6, I thought it was piss easy, now you guys have to ruin that :biggrin:

I thought I might well have got full marks to be honest, well before I read this thread. For the quartiles one, I originally just did 12 (or whatever n was) x 0.5 (or 0.25/0.75) and then used that figure (i.e. the 3rd, 6th & 9th). But when I went through at the end, I changed it to what you guys have been saying, so 3rd+4th / 2 etc... I wasn't sure if I should have changed it at the time, but I'm pleased I did now :p:

I thought the normal distribution question was easy, because both points were 10 away from the mean (medium = mode = mean for normal distribution, question a)), so then you knew P(Z>210)=0.2 and P(Z<190)=0.2 as P(190<Z<210)=0.6. I can't remember what I worked the standard deviation to be, but I was fairly confident.

The random variable question was fairly easy, you could just work it out from the table, therefore P(T)=0 = 7/16, then the others were all 1/16 I think, can't remember fully.

I had a bit of difficulty with the probability question, but I ended up with an answer that looked very much right (i.e. all = 100, & enough in each segment). Did you guys get P(Dislikes three wines)= 0.01? I think that's what I put.

Reply 111

qut101

ANYONE GOT 200 FOR THE MEDIAN IN THAT NORMAL DISTRIBUTION QUESTION?

and btw i see many ppl complaining abt the histogram question.. At first i thot like most of u did.. but then again they gave 5 marks n like 2 pages to solve it.. so there must have been a trick so i just added up all the frequency n got 70.. so the frequency is ( classwidth*frequency density* 2) 2 sinnce its 140 runners all together.

FOR THE SKEWNESS IN the cigarette question any 1 got 1/3 ? n wat did u comment? i said slightly more ppl had increase ammount of that drug in their blood! lolx Is that correct?

Reply 112

gorilla_baby

9

omg...i didnt order the data, so i got that whole question wrong...do they give marks for error carried forward??? and i also forgot that each die had 4 faces, so my values for a,b,c,d were wrong..and the whole question was wrong too,..,...........i knew the test was way tooo easy to be true...now i knw why...those stupid examiners....why did WE have to order the data..they never did tht..not once in any past paper...hate them

Reply 113

DestinedToFail

1

Thinking back I think I have put a correct answer and then scribbled an incorrect answer underneath it. Will I lose all the marks for that question? I kind of ran out of time and started rushing.

Reply 114

blue_boy

I took Q2 to be the average of the 6th and 7th value, Q1 to be the third value and Q3 to be the 9th value. This means i got the median right but both the quartiles wrong (two marks dropped...). Then i used my Q1 and Q3 values to work out the rest of the question, and im fairly confident i did them well, but i obviously got slightly different answers to other people. Will i only drop the two marks, or will they mark the rest of the question as wrong?

Reply 115

Doji

17

Yes i got 200 for the median, as its 50%, and its the mean in ND's.

What did people get for 7 (a) the P(R=3 and B=0)i did 0.25 + 0.25 = 0.5 ...

Also i did the quartlies in as tupid way to get me 0.3333 as the skewness, but it was a weak +ve skew i guess.

Q7 P(C|A) , me and a few others got (3/100) / (96/100) = 1/32

Reply 116

Doji

17

Also I hope the general consensus here is it was relatively harder than a few years ... means better boundaries for us.

Reply 117

Doji

17

muell

Hi,

125, 160, 169, 171, 175, 186, 210, 243, 250, 258, 390, 420
these are the values after sorting them out (I think)

to work out the right term for q1 = (1/4)*12 = 3
3 is an intenger
therefore you take the average value of the third and the fourth term
so 0.5*(169+171)= 170
so q1= 170

I ve used similar methods to work out the other quartiles:
q2= 198
q3= 254

I am not sure if this is correct but that is how i did it :smile:

might be wrong though :p:

I did it the exact same was as you, but im fairly sure were probably wrong lol. Which means, you must have got 1/3 for your skewness value, because i did with those values.

March will reveal all i guess.

Reply 118

amir123

hey man...! i didn arrange the values for that median and quartile sum...! do u think i'll getr some marks for the workin or will i lose all 9 marks.... reply asap...

Reply 119

Doji

17

amir123

hey man...! i didn arrange the values for that median and quartile sum...! do u think i'll getr some marks for the workin or will i lose all 9 marks.... reply asap...

no one knows, you'll get method marks if its write, for knowing Q1 is 0.25 x 12 will get u a mark i think.

How many marks was that Q worth anyway? ... i don't think 9, more like 5 or 6.

Edexcel Statistics S1 Exam Jan 2008

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