Given that,
Total number of children = 65
The ratio of boys to girls is 3 :2.
To find,
The number of girls in the grade.
Solution,
Let there are 3x girls and 2x boys.
ATQ,
3x + 2x = 65
5x = 65
x = 13
So, no of girls = 3x
= 3(13)
= 39
Hence, there are 39 girls in the grade.