Logic Riddles

Logic riddles with answers involve looking at situations and making judgements about them by ruling out impossibilities. If you like solving maths puzzles, you will most probably like logic riddles as well.

Rickety Rope Bridge

Four people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for seventeen minutes. The bridge is too dangerous to cross without a flashlight, and it’s only strong enough to support two people at any given time. Each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the fourth takes 10 minutes to cross.

How do the campers cross the bridge in 17 minutes?

Riddle Answer

4 Gallons using 3 and 5 Gallon Jugs

You have two jugs. One holds exactly 3 gallons and the other 5 gallons of water. You have unlimited supply of water. How do you fill 4 gallons of water into the five-gallon jug?

Riddle Answer

Longer Line

You draw a line. Without touching it, how do you make the line longer?

Riddle Answer

The Lucas Ship Problem

“Every day at noon,” Lucas said, “a ship leaves Le Havre for New York and another ship leaves New York for Le Havre. The trip lasts 7 days and 7 nights. How many New York-Le Havre ships will the ship leaving Le Havre today meet during its journey to New York?

Riddle Answer

Past the Bridge Guard

A guard is stationed at the entrance of a bridge. He is tasked to shoot anyone who tries to cross to the other side of the bridge, and to turn away anyone who comes in from the opposite side of the bridge. You are on his side of the bridge and want to escape to the other side.

Because the bridge is old and rickety, anyone who tries to cross it does so at a constant speed, and it always takes exactly 10 minutes to cross.

The guard comes out of his post every 6 minutes and looks down the bridge for any people trying to leave, and at all other times he sits in his post and snoozes. You know you can sneak past him when he’s sleeping, but the problem is that you won’t be able to make it all the way to the other side of the bridge before he sees you (since he comes out every 6 minutes, but it takes 10 minutes to cross).

One day a brilliant idea comes to you, and soon you’ve successfully crossed to the other side of the bridge without being shot. How did you do it?

Riddle Answer

Logic Riddles

Rickety Rope Bridge

4 Gallons using 3 and 5 Gallon Jugs

Longer Line

The Lucas Ship Problem

Past the Bridge Guard

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