Test your skills of deduction with the January 2025 edition of Riddle Me This: The Bridge and Torch Problem

Four engineers need to cross a narrow bridge at night. They have one flashlight, and the bridge is too dangerous to cross without it. The bridge is only strong enough to hold two people at a time.

Each engineer walks at a different speed:

Engineer A takes 1 minute to cross.

Engineer B takes 2 minutes to cross.

Engineer C takes 5 minutes to cross.

Engineer D takes 10 minutes to cross.

When two people cross the bridge together, they must move at the slower person’s pace. For example, if A and D cross together, it takes 10 minutes.

What is the minimum time needed for all four engineers to cross the bridge? How can they achieve it?

Click to Reveal Answer