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Mathematics 9 Online
OpenStudy (anonymous):

ABCDEFGHIJKLMNOPQRSTUVWXYZ

ganeshie8 (ganeshie8):

familiar with box and whisker plots right ?

ganeshie8 (ganeshie8):

easy - start by sorting the given data in increasing order

ganeshie8 (ganeshie8):

Excellent ! below is the format for five number summary : `minimum -- IQR1 -- median -- IQR3 -- maximum`

ganeshie8 (ganeshie8):

finding minimum and maximum is trivial, just take the first value for minimum and the last value for maximum

ganeshie8 (ganeshie8):

Right, what about the other three measures ? know how to find them ?

ganeshie8 (ganeshie8):

Inter Quartile Range 1 I think its also called as 25th percentile or Q1

ganeshie8 (ganeshie8):

Q1, median and Q2 are just numbers may be watch this short video from khan : https://www.youtube.com/watch?v=BXq5TFLvsVw It explains clearly how to calculate the 3 numbers

ganeshie8 (ganeshie8):

Okay, I'll try... lets find the `median` first

ganeshie8 (ganeshie8):

median = middle value of the data set

ganeshie8 (ganeshie8):

15, 27, `28, 34`, 42, 52

ganeshie8 (ganeshie8):

take average of those two middle numbers to get the median

ganeshie8 (ganeshie8):

median = \(\large \dfrac{28+34}{2} = ?\)

ganeshie8 (ganeshie8):

Yes !

ganeshie8 (ganeshie8):

Q1 = middle value of first half

ganeshie8 (ganeshie8):

`15, 27, 28`, 34, 42, 52

ganeshie8 (ganeshie8):

whats the middle value of first half ?

ganeshie8 (ganeshie8):

Yep !! Q3 = middle value of second half 15, 27, 28, 34, 42, 52 Q3 = ?

ganeshie8 (ganeshie8):

Correct ! its called Q3

ganeshie8 (ganeshie8):

Looks like we got all the 5 numbers ?

ganeshie8 (ganeshie8):

arrange them in below format : `minimum -- Q1-- median -- Q3-- maximum`

ganeshie8 (ganeshie8):

Looks good ^

ganeshie8 (ganeshie8):

we're done with part a

ganeshie8 (ganeshie8):

mean = (sum of all values)/(number of values)

ganeshie8 (ganeshie8):

Add up all the values, then divide by the number of values

ganeshie8 (ganeshie8):

how ?

ganeshie8 (ganeshie8):

check ur addition again 28 +34 +27+ 42+ 52+ 15 = 198 NOT 128

ganeshie8 (ganeshie8):

Oh I see, I should have told you what to add lol

ganeshie8 (ganeshie8):

Exactly !

ganeshie8 (ganeshie8):

Yes, mean = 33

ganeshie8 (ganeshie8):

right !

ganeshie8 (ganeshie8):

yes please

ganeshie8 (ganeshie8):

Notice that there are 3 columns in the given table

ganeshie8 (ganeshie8):

Fill the first column with the given data values

ganeshie8 (ganeshie8):

x -------------- 28 34 27 42 52 15

ganeshie8 (ganeshie8):

order doesn't matter... just take the given data set as it is..

ganeshie8 (ganeshie8):

yea, lets figure out what to put in second column

ganeshie8 (ganeshie8):

\(\overline{X} = \text{mean} = 33\)

ganeshie8 (ganeshie8):

yes !

ganeshie8 (ganeshie8):

put it in the table next to x column

ganeshie8 (ganeshie8):

x x-33 -------------- 28 -5 34 1 27 -6 42 9 52 19 15 -18

ganeshie8 (ganeshie8):

square each value in second column

ganeshie8 (ganeshie8):

right

ganeshie8 (ganeshie8):

Looks good

ganeshie8 (ganeshie8):

add them and you're done !

ganeshie8 (ganeshie8):

25 1 36 81 361 324 -----------

ganeshie8 (ganeshie8):

we use the result from part C for calculating standard dviation

ganeshie8 (ganeshie8):

standard deviation = \(\large \sqrt{\dfrac{(x-\overline{x})^2}{n}}\)

ganeshie8 (ganeshie8):

\(n\) = number of values in the data set

ganeshie8 (ganeshie8):

how ?

ganeshie8 (ganeshie8):

standard deviation = \(\large \sqrt{\dfrac{(x-\overline{x})^2}{n}} = \sqrt{\dfrac{828}{6}} = \sqrt{138} \approx 11.75\)

ganeshie8 (ganeshie8):

standard deviation = \(\large \sqrt{\dfrac{\color{red}{\sum} (x-\overline{x})^2}{n}} = \sqrt{\dfrac{828}{6}} = \sqrt{138} \approx 11.75 \)

ganeshie8 (ganeshie8):

np :)

ganeshie8 (ganeshie8):

I'll try, ask...

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