its simple formula :
N*D<R+N where N= total number of processes , D= each process need
R= resoures available
so in this problem N= 'N' number of processes
D=3 and R=6
so N*3<6+N
so 3N<6+N by solving this equation u will get
2N N<3
therefore N should be 2
u can aply this formula for other GATE 1998 CS and GATE 2005 CS
its simple formula :
N*D<R+N where N= total number of processes , D= each process need
R= resoures available
so in this problem N= 'N' number of processes
D=3 and R=6
so N*3<6+N
so 3N<6+N by solving this equation u will get
2N N<3
therefore N should be 2
u can aply this formula for other GATE 1998 CS and GATE 2005 CS