Question 1042925
There are (8 C 1)*(10 C 1) = 8*10 = 80 ways to form a pairing of a boy and a girl. 


This is out of 18 C 2 = 153 ways of picking 2 students.


The probability is therefore 80/153 = 0.52287581699347


Which is roughly 52.288%. 
So about roughly half of the time, you expect a pair to consist of one boy and one girl.