The number of ways in which a mixed double tennis game can be arrenged amongst 9 married couples if no husband and wife play in the same game is

• we have 9 males and 9 females
  first select 2 males from 9 males = 9c2 ways
  and we will left with only 7 females (as we have to leave the spouses of the males we have selected) = 7c2 ways
  and we can arrange these 4 people in 2 ways
  so total 2 * 9c2 * 7c2 =72 * 21 = 1512
• 9 years agoHelpfull: Yes(5) No(0)
• n!(1-1/1!+1/2!-1/3!+............+(-1)^n/n!)=133496(n=9)
• 11 years agoHelpfull: Yes(1) No(0)