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.
For any probability the formula is

. In this case we have 4 desired outcomes (the odds, 1, 3 and 5, and also 6) out of 6 total sides, so our probability

.
Mutually exclusive means the events cant occur at the same time. In our case it is not possible to roll both a 6 and an odd number at the same time since 6 is even. Therefore the events ARE mutually exclusive.
Combine the two parts and C is the correct answer. <span />