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

 

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

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

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{sumleft(M.fight)}{sum f} = ( up to 1 decimal place )

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Height 120 - 130 130 - 140 140 150 150 160 Frequency 10 160 - 170 8 253