Crossing the Bridge: McDonald's Caterers and a Calculus Class Party

[apaulo]

McDonald's is catering dinner for a Calculus class party that starts in 17 minutes and the caterers must cross a bridge to get there. All four of them start on the same side of the bridge. You must help them across to the other side. It is night. There is only one flashlight. A maximum of 2 people can cross at on time. Any Party, who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked together at a rate of the slower man's pace. It takes Ronald McDonald 1 minute to cross, the Hambugular 2 minutes to cross, ther French Fry Guy 5 minutes to cross, and Grimace 10 minutes to cross. For example: if Ronald and Grimace walk across, 10 minutes have elapsed wehn they get to the other side of the bridge. If Grimace then returns with the flashlight, a total of 20 minutes have passed and you have the mission. Good luck! Those Calculas students are hungry! Note: There is no trick to this and all 4 must attend the party.

 

[Delta]

I would inform the manager that they need to be more disciplined in time keeping, particularly 10 minute grimace. Afterall they are losing customers here.

Seriously though here's my answer.

Ronald and Grimace walk across taking 10 minutes. They shine the flashlight back at the other two to follow, which will take them 5 minutes. Then they have two minutes to spare.

 

[iNCREDiBLE]

It takes Ronald McDonald 1 minute to cross, the Hambugular 2 minutes to cross, ther French Fry Guy 5 minutes to cross, and Grimace 10 minutes to cross.


(->) Ronald McDonald and Hambugular: 2min.
(<-) Ronald McDonald: 1min.
(->) French Fry Guy and Grimace: 10min
(<-) Hambugular: 2min.
(->) Ronald McDonald and Hambugular: 2min.

Total: 17min.