4.37 A purchasing office is to assign a contract for computer paper and a contract for microcomputer disks to any one of three firms bidding for these contracts. (Any one firm could receive both contracts.) Find the probability that a Firm I receives a contract given that both contracts do not go to the same firm.

b Firm I receives both contracts.

c Firm I receives the contract for paper given that it does not receive the contract for disks.

What assumptions have you made?