Case 01 · logic · Easy · About 5–8 minutes
Rain has kept the night couriers indoors. Four parcels are waiting in a row of numbered cabinets. The clerk remembers who owns each cabinet and what each parcel contains, but the labels have washed away.
You have the clerk's notes. Rebuild the delivery list before the couriers leave.
The cabinets are numbered 1, 2, 3, 4 from left to right. Ada, Ben, Cy, and Dee each own one cabinet. Each cabinet contains exactly one different object: a book, a map, a key, or a bell.
- Ben owns cabinet 1.
- Dee's cabinet is immediately next to Ben's.
- Cy's cabinet is immediately to the right of Ada's.
- The book is in cabinet 4.
- The key is immediately to the right of the map.
- The bell and the key are not in neighboring cabinets.
Which courier and which object belong to each cabinet? “Immediately” means consecutive cabinet numbers. There are no shared cabinets and no objects outside the row.
For a compact working sheet, write the numbers across a page. Give each number two spaces: one for a courier and one for an object. A fact about the couriers does not automatically place an object.
Hint 1 - reveal when you want a nudge
Place Ben and Dee first. The remaining adjacent pair must hold Ada and Cy.
Hint 2 - reveal when you want a nudge
With the book fixed at 4, the map–key pair has only two possible positions. Test the bell in each.
Reveal the solution and explanation
The finished row is 1: Ben, bell; 2: Dee, map; 3: Ada, key; 4: Cy, book.
Ben occupies 1. Dee must be next to him, so Dee occupies 2. The remaining couriers, Ada and Cy, must fill 3 and 4 in that order.
Now consider the objects separately. The book uses 4. The adjacent map–key pair can therefore occupy either 1–2 or 2–3. If it occupies 1–2, the bell must use 3. That would put the bell next to the key in 2, violating the last clue.
The pair must occupy 2–3 instead. This leaves the bell in 1. Every person and object has a place, and each clue is satisfied. The two possible object-pair placements have both been checked, so there is no second complete arrangement.
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