প্রশ্ন ও সমাধান

Exactly six RAB officers - S, T, U, X, Y, and Z- take turns watching a suspect. To minimize the chance that the suspect will observe them or will escape their surveillance, the officers will operate according to the following conditions:There must be exactly two officers watching the suspect at all times.Whenever the suspect travels by car, either U or X must be one of the two officers watching, but U and X cannot take a turn together.Whenever the suspect travels by train, either Tor Z must be one of the two officers watching, but T and Z cannot take a turn together.If Z is one of the officers watching the suspect, S must be the other officer watching the suspect. S and X cannot take a turn together watching the suspect.If a pair of officers was watching while the suspect traveled by car, and the same pair of officers continued watching after the suspect began to travel by train, one member of that pair of officers must have been