Quiz III

[ASB]

Ok....here's a logic puzzle for yous...

Alex
Billy
Claire
Denise

need to cross a bridge. They all take different times to cross: -

Alex = 1 min
Billy = 2 mins
Claire = 4 mins
Denise = 8 mins

They only have one lantern between them, but the bridge will only hold 2 people at once. When travelling in a pair, they travel at the slowest speed of the 2.

How can all people get accross the bridge, always with a lantern, in 15 minutes?

Microsoft interview question.

[gingerjedi]

There's a place down the road from me called Uphill. Apparently they have a horticultural society rather than the Uphill gardening club.

Not noticed that.

Have you tried Dimitri's Bistro?

[Mich the Tester]

Ok....here's a logic puzzle for yous...

Alex
Billy
Claire
Denise

need to cross a bridge. They all take different times to cross: -

Alex = 1 min
Billy = 2 mins
Claire = 4 mins
Denise = 8 mins

They only have one lantern between them, but the bridge will only hold 2 people at once. When travelling in a pair, they travel at the slowest speed of the 2.

How can all people get accross the bridge, always with a lantern, in 15 minutes?

Easy. Alex grabs a laptop and looks it up on Wikipedia while the others start.

[Pogle]

Easy. Alex grabs a laptop and looks it up on Wikipedia while the others start.

Bugger, and I'd bothered to work it out

[OwlHoot]

Ok....here's a logic puzzle for yous...

Alex
Billy
Claire
Denise

need to cross a bridge. They all take different times to cross: -

Alex = 1 min
Billy = 2 mins
Claire = 4 mins
Denise = 8 mins

They only have one lantern between them, but the bridge will only hold 2 people at once. When travelling in a pair, they travel at the slowest speed of the 2.

How can all people get accross the bridge, always with a lantern, in 15 minutes?

Some of those Microsoft questions are stinkers, but this one is a piece of piss because obviously the fastest person should go on each trip to minimize the time they take returning on their own with the lamp.

For some real counterintuitive results relating to journey times and speeds, see a couple of articles on Terence Tao's blog:

An airport-inspired puzzle

Sailing into the wind, or faster than the wind

[ASB]

Not noticed that.

Have you tried Dimitri's Bistro?

Not been for a couple of years, but it always used to be good (if you like greek of course). So convenient to nip round the corner to sands for a figt and a stabbing after too. I think sands is rather better these days but when I used to go about 10 years ago it often got pretty scary.

[ASB]

Some of those Microsoft questions are stinkers, but this one is a piece of piss because obviously the fastest person should go on each trip to minimize the time they take returning on their own with the lamp.

Err, no.

[Doggy Styles]

Some of those Microsoft questions are stinkers, but this one is a piece of piss because obviously the fastest person should go on each trip to minimize the time they take returning on their own with the lamp.

I haven't looked this up. How does your solution work? I make it:

Alex(1) + Denise(8) = 8
Alex(1) returns with lantern = 9
Alex(1) + Claire(4) = 13
Alex(1) returns with lantern = 14
Alex(1) + Billy(2) = 16 minutes

[Drewster]

Err, no.

[Loading Shotgun mode]
Ker-Chick..... BOOM
[/Loading Shotgun mode]

I believe the phrase you are looking for is Shot and Burned!

[SallyAnne]

You have to do it in 15 seconds, not 16.