Interpolation - check where i'm going wrong? Watch

~the_one~
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#1
Report Thread starter 12 years ago
#1
Ah every question on interpolation i get wrong, no matter how hard i try to get it, so would really help if you could tell me where i'm going wrong.

e.g. (example made up by me)

x ....... F
0-5....... ... 3
5-9 ...... ... 7
10-14 ....... 9
15-19 ....... 5

So median value is 12th value : so in the 10-14 class

it's 2 of the way along in that class so 9/5 = 1.8 x 2 = 3.6

therefore 3 + 7+ 3.6 = 13.6
so the median is 13.6 right/wrong:confused:

OR another way is using the equation

b + {(1/2n - f) / fc} x c

where b: lower class boundary of median class
f: sum of all freq below median class
fc: freq of median class
c: width of median class.


9.5 + {(12 x 10) / 9} x 5 = 161.666 WHAT :eek:


As you can see i need help!
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footballhead
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#2
Report 12 years ago
#2
dude what the hell are u doing, sloppy sloppy
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~the_one~
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#3
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#3
you could at least help? So what am i doing wrong?
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footballhead
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#4
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#4
even the calculation uve written is calculated wrong

9.5 + (1/2 x 25-10)/9 x 5 = 13 2/3

type the brackets in your caculator first .5 x 7.5 then multiply by 5 then add 9.5
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Desi
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#5
Report 12 years ago
#5
is the answer 10/9 + 9.5
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Desi
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#6
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#6
for the median that is
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~the_one~
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#7
Report Thread starter 12 years ago
#7
Footballhead thanks for the help, so i got it right the first way?

The second way i did times it buy 5 then add 9.5 i just couldnt write it out like that.

OMG i just figured out how you did it (took me a while): you take 1/2 (n-f) not (1/2 x n) - f ?
Am i right...
panicing now..
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footballhead
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#8
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#8
ok crap what did i do wrong
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footballhead
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#9
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#9
did i get the answer right mate?

page 33 of ure s1 book

,median = b + (1/2 n - f/ fm) x w

so if u wanna find the q1 would u use 1/4n??
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Desi
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#10
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#10
am i rite? lol whose rite???
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~the_one~
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#11
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#11
I dont know what the answer is, i was asking you to work it out!!
I'll try again tomorrow!
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footballhead
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#12
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#12
this is what happens when they let us idiots take stats!!!
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Desi
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#13
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#13
i think my answer is correct
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gyrase
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#14
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#14
answer is 13.6 (or 13 2/3)

And i dont even have to do any calculations to tell that; you can tell from the table given.
duh!
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Desi
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#15
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#15
?????? isn;t it 9.5+(12- 10 / 9) * 5

and that gves 10/9 + 9.6
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Desi
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#16
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#16
yeh wt u on about 13. 6 lol?????
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Desi
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#17
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#17
i meant 10/9 + 9.5
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username51312
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#18
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#18
I got 10.611
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Desi
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#19
Report 12 years ago
#19
exactly................nice one dev u mite wanna do sum calculations next time
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username51312
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#20
Report 12 years ago
#20
Oh and can anyone explain how you done calculations witjout using formula? Or just say how is called that thing or topic.
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