The following is the table shows the grouped data, in classes , for the height of 50 people. ( f = n )

height (in cm) - classes frequency

120 - 130 2

130 - 140 5

140 - 150 25

150 - 160 10

160 - 170 8

a) Calculate the mean of the height of 50 people.

b) Calculate the standard deviation of the height of 50 people.

a)

height (in cm) - classes frequency (f) Mid Point (M) M x f

120 - 130 2

130 - 140 5

140 - 150 25

150 - 160 10

160 - 170 8

f = M. f =

Mean of Height ( \large \overrightarrow{x} ) = \frac{\sum\left(M.f ight)}{\sum f} = ( up to 1 decimal place )

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