In an examination average marks obtained by the girls of a class is 75 and the average marks obtained by the boys of the same class is 72 . If the girls and boys are in the ratio 3 : 4 , average marks of the whole class (approx.) is:

73.2

   Ratio of                Boys              Girls

                                 4       :          3            = 7 ( sum of number of boys and girls )

  Average of              72                 75

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

  Total   =            72 × 4             75 × 3         

  Total   =             288                  225

  Average  (combined) = \(\frac{288+ 225}{7}\) = 73.2 ( approx )