This Impossible Bridge Riddle Will Test Your Reasoning Ability To The Max

Riddle solving is a useful way to test the analytical ability of your mind. Since engineers also tend to be competitive about everything, how about an intriguing riddle challenge that will challenge your minds in a good way? Here it is:

Four people are running away from zombies. They have seventeen minutes to cross a bridge that will take them to safety. The bridge is able to hold a maximum of two persons at the same time, and one of them has to cross while holding a lantern because otherwise the visibility is poor. The four people include you who can cross the bridge at one time, a lab attendant who can cross the bridge in two minutes, a janitor who can cross in five minutes and the old professor who can cross in ten minutes. All four people have to be safe across the bridge by the end of seventeen minutes or else a zombie will step on it and break it. There are no tricks involved like swimming or going gangsta against the zombies like Resident Evil. Your only retribution is pure logic.

While there are more challenging riddles available in the market, this is an interesting one because of the lantern. It is necessary while crossing the bridge. The game is all about the position of yourself, the lab attendant and the lantern. So, give a deep thought and don’t forget to save your university fellows. Although I wouldn’t mind leaving the professor behind if he had been grilling you in academics. The old guy is too slow anyway and will get the rest of you killed!

1. Sanjaya says:

We should fight the zombi

2. Don Lance says:

First to go: me and the lab assistant, 2 mins. I come back with the lamp in 1 min. Total of 3 mins.
2nd, the professor and the janitor crosses the bridge in 10 mins then the lab assistant comes back for me with the lamp in 2 mins. Total of 12 mins.
We then cross the bridge in 2 mins.

So, 3+12+2 = 17 minutes

Just enough time to cut the rope.

Not so impossible after all, huh?

3. Elliott Coker says:

The Lab assistant carries the professor and lantern across in 2 minutes then returns and carries the janitor across and returns. 8 minutes have passed. I carry the lab assistant across. 9 minutes have passed.

4. Eyüp Daban says:

1+2=2 minutes go across
1 minute back
5+10= 10 minutes go across
2 minutes back
2+1=2 minutes go across

5. Patrick stegeman says:

At first 1 and 2 than 1 go’s back and 5 and 10 go then 2 come’s back. And 1and 2 go again.

6. Tanaji says:

first 1 and 2 will cross bridge = 2 min
next 1 will go back = 3 min
next 10 and 5 will go = 13 min
next 2 will go back = 15 min
next 1 ,2 = 17 min

7. Ahmed says:

me+lab attendant -2
me -1
janitor + professor -10
lab attendant -2
me+lab attendant -2

8. M says:

Let the professor go first holding the lantern and send one person with him. By the time the faster person crosses, the professor is still holding the lantern so another person can go. Do this one more time and you have 3 people over in 8 minutes while the professor comes in at 10. Is this right?

9. saurabh singh says:

first of all I will go along with lab attendent with lantern, it will require 2 minutes.
now
I will return with lantern in 1 minute and
send the janitor and professor, they will take 10 minutes.
now the lab attendent will come back to me holding lantern in 2 minutes
we will cross the bridge in 2 minutes.
total time taken =17 minutes