Answer:
There are 18 girls in a group that has 16 boys.
Step-by-step explanation:
Total number of girls
=
81
Total number of boys
=
72
Ratio of girls :boys of whole grade
=
81
:
72
=
9
:
8
The grade is split into groups maintaining same ratio of whole grade ie;
9
:
8
Let the group having
16
boys have
x
girls:
9
8
=
x
16
9
8
×
16
=
x
9
×
2
=
x
x
=
18
girls
