Logic Quiz

[SID_NY]

Re: Logic Quiz

@MustafaQuraishi

I thought i had cleared these assumptions in the update but i guess they weren’t cleared.

1. There is only one light source. Only one. there is no other option or no hidden way of getting another light source
2. A person can’t cross the bridge without a light source. Most of you people tried to gave the light source to D and paired it with another person (C). But in this case, C would only be able to cross the birdge at the speed of D since D is the one who is holding the light source. C can’t walk past D because if he does, he would be leading and wouldn’t have the light source to see. Similarly, If D is in the middle of the bridge with light source, another person from another end can’t start because he wouldn’t have the light source. The people at the other side has to wait for someone to bring the light source back to them.

To simplify,

1. A pair can only cross the bridge at the speed which is slowest between them. i.e. if A and D are crossing the bridge then A’s speed is irrelevant since D is walking at slower speed.
2. A single person can’t start the walk without having the light source. Consider the bridge as river and light source as boat. The speed of the boat would be the rowing speed of the slowest person.
3. There is only one light source. If A and D is carrying it and they reached the other end, then one of them has to bring the light source to the starting end to bring other people

I hope its clear now.

With all these explanations the answer that I came up with is “31” assuming there is one light source and whoever is crossing the bridge must either himself or his partner has to carry it. But i still think its a very inefficient number so there gotto be a shorter number than this but cant think of anything right now.