[" 9.In how many ways can a lawn tennis mixed double be made up from seven married "],[" couples if no husband and wife play in the same set? "]

If the number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is K , then greatest prime divisor of K is __________.

If the number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is K , then greatest prime divisor of K is __________.

Number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is a. 240 b. 420 c. 720 d. none of these

Number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is a. 240 b. 420 c. 720 d. none of these

Number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is a.240 b.420 c.720 d.none of these

Number of ways in which a lawn-tennis mixed double be made from seven married couples if no husband and wife play in the same set is a. 240 b. 420 c. 720 d. none of these

In how many ways can a mixed doubles game in tennis be arranged from 5 married couples, if no husband and wife play in the same game?