S1 area of a histogram =k x frequency

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Core
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Please someone tell me what k is...
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zog170
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Class Width
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Core
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(Original post by joenye)
Class Width
Also what does the interquartile range mean.
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Zakky
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(Original post by Core)
Also what does the interquartile range mean.
Upper Quartile - Lower Quartile

Q3-Q1
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Core
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(Original post by Zakky)
Upper Quartile - Lower Quartile

Q3-Q1
I know how to calculate it but the book said (this is after it calculated the interquartile range as 1) "this means 50% of the data lies within 1 of each other, i don't understand.
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sohail.s
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(Original post by Core)
I know how to calculate it but the book said (this is after it calculated the interquartile range as 1) "this means 50% of the data lies within 1 of each other, i don't understand.
well

any data below the lower quartile is equal to 25% of the data
any data above the upper the quartile is equal to another 25% of the data.
therefore any data in between these two boundaries call them, is 50% of the data, and since IQR - UQ- LQ then IQR represents 50% of data.

EDIT: Also k is not class width
k is a constant

Basically Area is proportional to frequency
In an equation that means Area = k x frequency (getting rid of the proportionality sign)
HAve a try at the following question: Jan 2008 S1 Question 3 if you havent done it already
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Core
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(Original post by sohail.s)
well

any data below the lower quartile is equal to 25% of the data
any data above the upper the quartile is equal to another 25% of the data.
therefore any data in between these two boundaries call them, is 50% of the data, and since IQR - UQ- LQ then IQR represents 50% of data.
So if the interquartile range is 1, then no data within the interquartile range can be more than 1 larger or one smaller than the other? Also frequency density.. = frequency/class width, is this only if class width =1?
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Core
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I have so much confusion with histograms..
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Wick3d
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Just remember the formulae, so Frequency Density = Frequency / Interval
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Core
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(Original post by Wick3d)
Just remember the formulae, so Frequency Density = Frequency / Interval
interval..? the class width? I just came back from my exams today and sat in the coldest part of the room, my heads a-bit shot.
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sohail.s
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(Original post by Core)
So if the inter quartile range is 1, then no data within the inter quartile range can be more than 1 larger or one smaller than the other? Also frequency density.. = frequency/class width, is this only if class width =1?
not sure about IQR = 1, you might be confusing IQR with standard deviation, th IQR is only used if data is skewed but even then it really doesnt have much useful mathematical properties, it just gives an indication of how spread out the data is, a small iqr is a small spread, a large IQR is a large spread basically.

Histograms.

Area = Class Width * Frequency Density
and since area=frequency Frequency/Class Width = Frequency Density
Works all the time
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Wick3d
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(Original post by Core)
interval..? the class width? I just came back from my exams today and sat in the coldest part of the room, my heads a-bit shot.
Interval represents what is given in the question so one it could be class width.
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sohail.s
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(Original post by Core)
interval..? the class width? I just came back from my exams today and sat in the coldest part of the room, my heads a-bit shot.
same thing.
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Core
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(Original post by sohail.s)
not sure about IQR = 1, you might be confusing IQR with standard deviation, th IQR is only used if data is skewed but even then it really doesnt have much useful mathematical properties, it just gives an indication of how spread out the data is, a small iqr is a small spread, a large IQR is a large spread basically.

Histograms.

Area = Class Width * Frequency Density
and since area=frequency Frequency/Class Width = Frequency Density
Works all the time
what about when the class width isn't one? does area still = frequency
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sohail.s
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(Original post by Core)
what about when the class width isn't one? does area still = frequency
area is always equal to frequency(more precisely its proportional but if k=1 then its equal)
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Core
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Thanks guys reps all round
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Core
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1 more question, how do i settle my body down after an exam, i can't think straight.
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sohail.s
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(Original post by Core)
1 more question, how do i settle my body down after an exam, i can't think straight.

go home, relax, maybe go to bed or watch TV, just keep your mind off the exam and avoid discussion though its very temtping
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Core
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(Original post by sohail.s)
go home, relax, maybe go to bed or watch TV, just keep your mind off the exam and avoid discussion though its very temtping
Got another exam in twodays, so i have to study.
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16ARTER
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(Original post by sohail.s)
well

any data below the lower quartile is equal to 25% of the data
any data above the upper the quartile is equal to another 25% of the data.
therefore any data in between these two boundaries call them, is 50% of the data, and since IQR - UQ- LQ then IQR represents 50% of data.

EDIT: Also k is not class width
k is a constant

Basically Area is proportional to frequency
In an equation that means Area = k x frequency (getting rid of the proportionality sign)
HAve a try at the following question: Jan 2008 S1 Question 3 if you havent done it already
The May 2009 s1 paper edexcel Question 3 is very confusing and i still don't understand how to get the answer eventhough i have looked at the markscheme. It is about finding the height and width of the bar. Also i don't get area = k*frequency?

Thanks
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