FILE No.120Unsolved
The electronic lock on a museum storeroom unlocks automatically in a power outage, for safety, and locks itself again when power returns. While power is on, it opens only with a registered key. The registered keys' usage log shows no use at all that night.
That night there was a 10-minute blackout in the neighborhood, from 11:10 p.m. to 11:20 p.m. The guard made two rounds. At 11:00 the treasure was in the storeroom. At 11:30 it was gone. At 11:30 the door was locked.
When was it stolen?
If you get stuck, open the hints one at a time, in order.
Was the treasure there at the 11:00 round?
From when to when was the door open?
After 11:20, could someone enter without a key?
When was it stolen?
Choose the answer closest to the truth.
Between 11:10 and 11:20
The answer is "Between 11:10 and 11:20."
The treasure was there at 11:00, so the theft came after 11:00. When power returned at 11:20, the door locked again and could be opened only with a registered key. That key was not used even once that night.
The door was open only during the 10-minute blackout. That was the only time the theft was possible.
Because "it was locked" sounds as if it was locked the whole time.
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