Given:-Total number of students for course D = 35% of 1200 = 420
Number of girl students for course D = 30% of 800 = 240 ,
Number of boy students for course D = Total number of students for course D - Number of girl students for course D = 420 − 240 = 180
Required ratio = Number of boy students for course D : Number of girl students for course D
Required ratio = 180 : 240 = 3 : 4
