
Mike C. answered 08/02/13
Enthusiastic Tutor for Middle and High School Students
You're first picking 6 people out of 20 possible candidates, so the total number of possible 6-person combinations is 20C6. By the same logic, the number of possible male combinations are 10C2 and the female combinations 10C4; these two are independent events, so the number of possible 2-man and 4-woman combinations are (10C2)(10C4).
The possibility of this happening, then, is (10C2)(10C4)/20C6.