It is required to seat $5$ men and $4$ women in a row so that  the women occupy the even places. How many such arrangements are possible?

Since women has to occupy even places so first of all arrange 5 men in the row which can be done in $5$ ways and then put women on the places between each men and then arrange these women which can be done in $4!$ ways 

Hence total number of ways $=4!5!$