Analyze the Composition and Clues for Tour 4

• Tour 4 is described as visiting "factories Y, Z, and a mystery location."
• The guide on Tour 4 states: "We are at a factory that makes gadgets, a factory that makes widgets, and a factory that makes widgets."
• From the initial list, we know that subcontractor Y makes gadgets and subcontractor Z makes widgets.
• To match the guide's statement of one gadget-maker and two widget-makers, the mystery location must also be a widget-maker.

Apply the Clue About the Mystery Location's Identity

• Clue 7 states: "The mystery location on Tour 4 is not a factory already listed on the tours."
• The factories listed on Tours 1, 2, and 3 are A, B, C, D, E, F, G, and H.
• Therefore, the mystery location cannot be any of these eight factories.

Identify the Pool of Candidates

• Since the mystery location cannot be one of the eight main factories (A-H), the only remaining possibilities are the three subcontractors: X, Y, and Z.
• However, the tour is explicitly "Y, Z, and a mystery location," which implies three distinct locations. This means the mystery location cannot be Y or Z.

Conclusion

• By eliminating the factories (A-H) and the subcontractors already named on the tour (Y and Z), the only possible candidate for the mystery location is subcontractor X.
• Let's verify this: X is a subcontractor (not a factory A-H) and makes widgets, which perfectly fits all the conditions derived from the clues.

Therefore, the hidden subcontractor revealed on the tour is X.