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 15.4 years. The ratio of the number of boys to the number of girls in the class is:-

Let the ratio be x : y
Total boys = 16.4 X x
Total girls = 15.4 X y
Total number of students in class = 16.4x + 15.4y
The average age of all students is 15.8
The total age of boys is 15.8x
The total age of girls is 15.8y
16.4x + 15.4y = 15.8x + 15.8y
0.6 x = 0.4 y
x/y = 0.4/0.6 = 2/3