The night watchman in a factory cannot guard both the safe in back and the cash register in front. the safe contains $6000, while the register has only $1000. tonight the guard fears a robbery; the probability that the thief will try the cash register is 0.8 and the probability the thief will try the safe is 0.2. if the guard is not present, the thief will take all the money. if the guard is present, the thief will go away empty handed. where should the guard be positioned in order to minimize the thief’s gains?