total no of ways in which all 7 can be seated =
7! waysnow,
if rohit sits at
first seat then remaining 6 can be seated in
6! ways if rohit sits at
middle seat then remaining 6 can be seated in
6! ways if rohit sits at
last seat then remaining 6 can be seated in
6! waysno. of ways in which rohit
doesnt sits in middle or at either ends =
7! - (6! + 6! + 6!) = 7! - 6!*3 = 6!(7-3)=6!*4=
2880Hope this helps.
_________________
Live as if your were to die tomorrow. Learn as if you were to live forever - Gandhi