Brainteaser

Old 08-26-2011, 05:32 AM
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My ds brought this one home from school yesterday. Have fun:

"U2" has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge.

You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown, etc. Each band member walks at a different speed. A pair must walk together at the rate of the slower man's pace.

Bono - 1 minute to cross
Edge - 2 minutes to cross
Adam - 6 minutes to cross
Larry - 10 minutes to cross

For example: If Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission.

Notes: There is no 'trick' behind this. It is a simple movement of resources in the appropriate order. There are two known answers to this problem.

This is based on a question Microsoft gives to all prospective employees. Microsoft expects you to answer this question in under 5 minutes.

I must warn you, you can really get caught up trying to solve this problem. Reportedly, one guy solved it by writing a computer program, although it took him 37 minutes to develop (compiled and ran on the first try through). Another guy solved it in three minutes. A group of 50, at Motorola, couldn't figure it out at all.

Good luck!!
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Old 08-26-2011, 06:13 AM
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approx 10 minutes to solve, IF this is correct?
BONO AND EDGE CROSS OVER WITH LIGHT........ 2 MINUTES
BONO COMES BACK WITH LIGHT................. 1 MINUTE
ADAM AND LARRY CROSSOVER WITH LIGHT........ 10 MINUTES
EDGE COMES BACK WITH LIGHT................. 2 MINUTES
BONO AND EDGE CROSSOVER WITH LIGHT......... 2 MINUTES

TOTAL TIME ELAPSED......................... 17 MINUTES!

and if this isn't it, well, I'd just FIRE Larry from the band, cause he's just too darn SLOW!!
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Old 08-26-2011, 06:17 AM
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Originally Posted by kountrykreation
approx 10 minutes to solve, IF this is correct?
BONO AND EDGE CROSS OVER WITH LIGHT........ 2 MINUTES
BONO COMES BACK WITH LIGHT................. 1 MINUTE
ADAM AND LARRY CROSSOVER WITH LIGHT........ 10 MINUTES
EDGE COMES BACK WITH LIGHT................. 2 MINUTES
BONO AND EDGE CROSSOVER WITH LIGHT......... 2 MINUTES

TOTAL TIME ELAPSED......................... 17 MINUTES!

and if this isn't it, well, I'd just FIRE Larry from the band, cause he's just too darn SLOW!!
ROFL, good one.

You got it!! 10 minutes, that's fantastic!!
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Old 08-26-2011, 06:29 AM
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Originally Posted by MommaDorian
Originally Posted by kountrykreation
approx 10 minutes to solve, IF this is correct?
BONO AND EDGE CROSS OVER WITH LIGHT........ 2 MINUTES
BONO COMES BACK WITH LIGHT................. 1 MINUTE
ADAM AND LARRY CROSSOVER WITH LIGHT........ 10 MINUTES
EDGE COMES BACK WITH LIGHT................. 2 MINUTES
BONO AND EDGE CROSSOVER WITH LIGHT......... 2 MINUTES

TOTAL TIME ELAPSED......................... 17 MINUTES!

and if this isn't it, well, I'd just FIRE Larry from the band, cause he's just too darn SLOW!!
ROFL, good one.

You got it!! 10 minutes, that's fantastic!!
I am so glad you solved this. My brain goes into panic mode then shuts down. I am so afraid my answer will look stupid.
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Old 08-26-2011, 07:10 AM
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Three minutes for me.
Bono & Edge - 2 minutes
Edge returns -2
Larry and Adam - 10
Bono returns 1
Bono and Edge 2

Same kountrykreation, except Bono and Edge reversed order of return.

It's scary that 50 businessmen couldn't do this.
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Old 08-26-2011, 10:58 AM
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DH and I were stuck on one of the ones that took the light across had to bring it back.... duh! Thanks for the brain teaser.

He just told me the one about the Fox, Goat and cabbage. Need to get them across the river, but you can't leave the Fox with the Goat nor the Goat with the cabbage. Can you get them all across?
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Old 08-26-2011, 03:04 PM
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:roll: I don't like story problems! Thanks for the answers.
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Old 09-28-2011, 08:30 AM
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wait till daylight!
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Old 09-28-2011, 08:52 AM
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Originally Posted by Phyllis nm
wait till daylight!
:thumbup:
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Old 09-28-2011, 09:01 AM
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Originally Posted by irishrose
It's scary that 50 businessmen couldn't do this.
Scary, but sadly, not surprising. I know way too many managers with degrees in business administration who cannot understand a simple profit-and-loss statement.
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