Four prospectors with only one lantern must walk through a mine-shaft. At most, two prospectors can travel together and any prospector in the shaft must be with the lantern. The prospectors, named Andrews, Blake, Johnson, and Kelly, can walk through the shaft in one minute, two minutes, four minutes, and eight minutes, respectively. When two walk together they travel at the speed of the slower prospector. How can the prospectors get through the mine-shaft in only 15 minutes?© BrainMass Inc. brainmass.com March 21, 2019, 4:46 pm ad1c9bdddf
Simple answer -
1. Send Andrews and Blake to the other shaft (2 mins).
2. Andrews comes back with lantern (1 min) ( total elapsed time 3 mins).
3. Send Johnson ...
Discussion of the solution to the prospectors/mineshaft problem. References are provided.