
Chapter 4
PB
Measures of Dispersion
145
4. 6 Standard deviation = 9 Quartile deviation = 7.5 Mean absolute deviation, that is, 6s = 9
QD = 7.5 MAD
5. Standard deviation =
5
Mean absolute deviation or
3
Quartile deviation, that is,
SD MAD=
5
or
3
QD
6. Range = 6 Standard deviation
R = 6s.
4.7 CHEBYSHEV’S THEOREM
Empirical rule applies only to normally distributed data. It has a wide range of application, but in
cases where data distribution is not normal or where the shape of the distribution is not known, its
application is restricted. Chebyshev’s theorem provides an answer to this problem. It was devel-
oped by Russian mathematician P. L. Chebyshev ...