Krishna
0

Step 1: Recall the formula of the mean of the grouped data

            NOTE: The mean (or average) of observations is the sum of the values of

              all the observations divided by the total number of observations.


            Let x_1, x_2, x_3............, x_n be observations with respective      

            frequencies f_1, f_2,............f_n


                    Mean = \frac{f_1x_1 + f_2x_2 + ........f_nx_n}{f_1 + f_2 +..........+ f_n}

                                              or

                                Mean = \frac{\Sigma f_ix_i}{\Sigma f_i}


Step 2: Re-organize given data in the table and find the sum of all observations.

                


             Sum of the values of all the observations   \Sigma f_ix_i = 1779

            Total number of observations \Sigma f_i = 30

        

              So, the mean = \frac{1779}{30}

                      Mean = 59.3