Question 1023411
 
Question:
5 particular boys and 5 particular girls are selected and placed in mixed pairs for tennis.Find the total number of different mixed pairs which can be made using these 10 children.
 
Solution:
Consider the case of one boy and 5 girls.  How many ways can we make a mixed pair? The answer is five.
What if we add one more boy to make 2 boys and 5 girls?  The number of mixed pairs is 5 for each boy, so 10.
Now consider 5 boys and 5 girls.  I am quite sure you have the answer by now.