Subject: mathqa
Question: the average age of students of a class is 15.8 years . the average age of boys in the class is 16.3 years and that of the girls is 15.4 years . the ration of the number of boys to the number of girls in the class is ?
Option: 
A: 2 : 3
B: 2 : 4
C: 2 : 6
D: 4 : 5
Answer: D