Page 11 - Math SL HB Sem 3

) Measure of spread/dispersion

Range The maximum value - the minimum value

E.g. for the data set: -1, 3, 3, 5, 7, 8, 9, '15, 23
)the range = 23 - (-7) = 24

IQR The upper quartile (Q:) - the lower quartile (Qr)
th
)Upper Quartile, 03: the value below which 75% of the d"ta rie = (i x (n + f )) value
th
lLower Quartile, ?,: the value below which 25% of the data lie = (i , 1" + f;) value

for the data set: - l 2a 5,7,8, 1 23
) 6,-
,,: , =3 Qt 9+15 IQR = qr-Qt = 9
2
lndicates how wide the data spread about the mean

Calculation:
For grouped data:
z@ -i)2 Z,' use the mid-inteta/al value
tt*tgrav.p eol o tl for k' multiplied by f
adq fL
(-= af Cr -i )'

Variance The squared value of standard deviation

Calculation:

, LG-DZ L,2
o- =-
II TL

-terseulles

-Provide subdivision into hundredths.

-Steps to find percentiles for ungroupred data?
*ht"
?r= !. n+ r)tL obcrr(*l;o n n = number of obscrvalions
(
loo r: percentile
Deciles

-Provide subdivision into tenths-

Di- r crt+D+L oJacroadbn

t6

le