the average age of students of a class is 15.8 years . the average age of boys in the class is 16.4 years and that of the girls is 15.1 years , the ratio of the number of boys to the number of girls in the class is
explanation : let the ratio be k : 1 . then , k * 16.4 + 1 * 15.1 = ( k + 1 ) * 15.8 < = > ( 16.4 - 15.8 ) k = ( 15.8 - 15.1 ) < = > k = 0.7 / 0.6 = 7 / 6 . required ratio = 7 / 6 : 1 = 7 : 6 . answer : a
divide(subtract(15.8, 15.1), subtract(16.4, 15.8))