FINDING MEAN FOR GROUPED DATA EXAMPLES

Question 1 :

If the mean of the following data is 20.2, then find the value of p

Mean  =  (610 + 20p)/(30 + p)

Mean  =  20.2

(610 + 20p)/(30+p)  =  20.2

610 + 20p  =  20.2(30+p)

610 + 20 p = 606 + 20.2p

20.2p-20p  =  610 - 606

0.2p  =  4

p  =  4/0.2

p  =  20

Question 2 :

In the class, weight of students is measured for the class records. Calculate mean weight of the class students using Direct method.

Solution :

Mean  =  2010 / 6

  =  335

Question 3 :

Calculate the mean of the following distribution using Assumed Mean Method:

Solution :

A = 25

Mean  =  A + ∑ fd/∑ f

=  25 + (270/63)

=  25 + 4.28

Mean  =  29.28

Question 4 :

Find the Arithmetic Mean of the following data using Step Deviation Method:

Solution :

Mean  =  A + (∑ fd/∑f) x c

=  32 + (-62/105) x 5

=  32 - 0.59 (5)

=  32 - 2.95

Mean  =  29.05

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