# S1 area of a histogram =k x frequency

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Class Width

**joenye**)Class Width

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#4

(Original post by

Also what does the interquartile range mean.

**Core**)Also what does the interquartile range mean.

Q3-Q1

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#6

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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.

**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.

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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(Original post by

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.

**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.

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(Original post by

Just remember the formulae, so Frequency Density = Frequency / Interval

**Wick3d**)Just remember the formulae, so Frequency Density = Frequency / Interval

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#11

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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?

**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?

Histograms.

Area = Class Width * Frequency Density

and since area=frequency Frequency/Class Width = Frequency Density

Works all the time

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#12

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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.

**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.

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#13

**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.

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(Original post by

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

**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

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#15

(Original post by

what about when the class width isn't one? does area still = frequency

**Core**)what about when the class width isn't one? does area still = frequency

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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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#18

(Original post by

1 more question, how do i settle my body down after an exam, i can't think straight.

**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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(Original post by

go home, relax, maybe go to bed or watch TV, just keep your mind off the exam and avoid discussion though its very temtping

**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

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#20

(Original post by

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

**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

Thanks

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