∵ g : S → S where S={1,2,3,4,5,6} Total number of onto function = 6 ! Given condition g(3)=2g(1) If g(1)=1, then g(3)=2 g(1)=2, then g(3)=4 and g(1)=3, then g(3)=6 There are only 3 possible cases Number onto functions = 3 × 4 ! Required probability =