Permutations & Combinations: Bankteller Problem

rickdundee
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Homework Statement


There are 6 males and 4 females awaiting to see a teller at a bank.

Only 4 people can be served at one time.
1) How many ways can four of the people be picked and served one at a time, if they must include two(2) men and two(2) women?


2) If indeed the four people are picked randomly, what is the probability that the four will include two (2) men and two (2) women?
This is the question I am confused about.


The Attempt at a Solution


My solution for Problem#1: (6 choose 2) * (4 choose 2) = 90
 
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How many ways can you pick 4 people out of the 4 men and 6 women (with no restriction on how many men or women there are)?
 
That would be 10c4
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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