All MAP Topics in One Session

A has 3 maps and B has 9 maps.All the 12 maps being distinct.Determine the number of ways in which they can exchange their maps if each keeps his initial number of maps.

If mapping f:A rarr B is one-one onto,then prove that mapping f^(-1):B rarr A is also one- one onto.

36.One mapping /function is selected at random from all the mappings of the set A={1,2,3,4,5) .Into itself.Find the probability that the mapping selected is one to one.