In an examination average marks obtained by the girls of a class is 85 and the average marks obtained by the boys of the same class is 87. If the girls and boys are in the ratio 4: 5, average marks of the whole class (approx.) is:

86.1

                          Girls             Boys

                            4        :        5

        Avg. marks   85               87

                         ------------------------

Total marks          340             435

            Avg    =  \(\frac{340+ 435}{9}\) = 86.1