Crossing a bridge

[Guest]

Four soldiers must cross a bridge and they know the enemy is not far behind. Only up to two can safely walk on the bridge at any time. There's only one flashlight among them, and it is necessary to use the flashlight to see while crossing.

The soldiers have various injuries and can only cross the bridge so fast.

The following are the fastest times that each can cross:

MSGT Moore: 1 minute

1LT Jackson: 2 minutes

PFC Diggs: 5 minutes

CPT Pruden: 10 minutes

What is the fastest time they can achieve in all safely crossing the bridge?

[Guest]

1.Jackson & Moore (2mins)

2.Moore comes back to give flashlight(1min)

3.Diggs & Pruden (10min)

4.Jackson comes back to give flashlight(2min)

5.Jackson & Moore (2min)

Total is 17 mins

Four soldiers must cross a bridge and they know the enemy is not far behind. Only up to two can safely walk on the bridge at any time. There's only one flashlight among them, and it is necessary to use the flashlight to see while crossing.

The soldiers have various injuries and can only cross the bridge so fast.

The following are the fastest times that each can cross:

MSGT Moore: 1 minute

1LT Jackson: 2 minutes

PFC Diggs: 5 minutes

CPT Pruden: 10 minutes

What is the fastest time they can achieve in all safely crossing the bridge?

[Guest]

Minimum Time taken by all 4 to cross the bridge will be 5 minutes as below:

1. Moore carries Jackson to other side & returns - 2min

2. Moore carries Diggs to other side & returns - 2 min

3. More carries Pruden to other side - 1 min

Above is with assumption that all being soldiers have been sufficiently trained & strong enough to carry one another

Hope not wrong within wording & logic of puzzle?

Four soldiers must cross a bridge and they know the enemy is not far behind. Only up to two can safely walk on the bridge at any time. There's only one flashlight among them, and it is necessary to use the flashlight to see while crossing.

The soldiers have various injuries and can only cross the bridge so fast.

The following are the fastest times that each can cross:

MSGT Moore: 1 minute

1LT Jackson: 2 minutes

PFC Diggs: 5 minutes

CPT Pruden: 10 minutes

What is the fastest time they can achieve in all safely crossing the bridge?

[Guest]

Minimum Time taken by all 4 to cross the bridge will be 5 minutes as below:

1. Moore carries Jackson to other side & returns - 2min

2. Moore carries Diggs to other side & returns - 2 min

3. More carries Pruden to other side - 1 min

Above is with assumption that all being soldiers have been sufficiently trained & strong enough to carry one another

Hope not wrong within wording & logic of puzzle?

I would assume that since the crossing time for each soldier is specified that this is the shortest period in which he can cross. Therefore no one can ride piggy-back on another soldier. Shortest crossing time = M Sgt + 1 Lt (2 min), M Sgt returns (1 min), Capt + PFC (10 min), 1 Lt returns (2 min), M Sgt + 1 Lt (2 min) for total of 17 minutes.

[Guest]

Answer is 12 minutes

Step 1 : Let the 10 mins guy start crossing...

Step 2 : After 5 minutes, let the 5 minute guy start..they reach the end at the same time

Step3 : Let the 2 minutes guy start

Step 4 : After a minute, let the one minute guy start...they reach at the same time..so in total 12 minutes

Glenn

Didn't you forget the flashlight?

[Guest]

I am only eleven...but here is my answer:

CPT Pruden starts crossing the bridge while at the end of the bridge MSGT Moore holds the flashlight pointing toward the end of the bridge(assuming that the light reaches across the bridge).PFC Diggs leaves along with Pruden.When PFC Diggs finishes the crossing, 1LT Jackson gets on while CPT Pruden is still walking.When 1LT Jackson finishes also, MSGT Moore sets the flashlight down (while it is still shining to the other side of the bridge) and begins walking across.When he is done walking, CPT Pruden is still walking since it takes him ten minutes to cross and the other mens' times only added up to eight minutes.When Pruden finishes it will have only been ten minutes!Then they just leave the flashlight behind.My answer is ten minutes.Then again, I am only eleven .

[Guest]

Four soldiers must cross a bridge and they know the enemy is not far behind. Only up to two can safely walk on the bridge at any time. There's only one flashlight among them, and it is necessary to use the flashlight to see while crossing.

The soldiers have various injuries and can only cross the bridge so fast.

The following are the fastest times that each can cross:

MSGT Moore: 1 minute

1LT Jackson: 2 minutes

PFC Diggs: 5 minutes

CPT Pruden: 10 minutes

What is the fastest time they can achieve in all safely crossing the bridge?

Oh... I've done these before...

17 minutes

[Guest]

I am only eleven...but here is my answer:

CPT Pruden starts crossing the bridge while at the end of the bridge MSGT Moore holds the flashlight pointing toward the end of the bridge(assuming that the light reaches across the bridge).PFC Diggs leaves along with Pruden.When PFC Diggs finishes the crossing, 1LT Jackson gets on while CPT Pruden is still walking.When 1LT Jackson finishes also, MSGT Moore sets the flashlight down (while it is still shining to the other side of the bridge) and begins walking across.When he is done walking, CPT Pruden is still walking since it takes him ten minutes to cross and the other mens' times only added up to eight minutes.When Pruden finishes it will have only been ten minutes!Then they just leave the flashlight behind.My answer is ten minutes.Then again, I am only eleven .

Lol you don't need to keep telling us that you're only eleven, I think we got it. Anyways, your answer makes sense... and the flashlight wouldn't need to remain behind either... so good work

[Guest]

I am only eleven...but here is my answer:

CPT Pruden starts crossing the bridge while at the end of the bridge MSGT Moore holds the flashlight pointing toward the end of the bridge(assuming that the light reaches across the bridge).

Nah, can't make that assumption. Nice thinking outside the box, though.

[Guest]

Answer is 12 minutes

Step 1 : Let the 10 mins guy start crossing...

Step 2 : After 5 minutes, let the 5 minute guy start..they reach the end at the same time

Step3 : Let the 2 minutes guy start

Step 4 : After a minute, let the one minute guy start...they reach at the same time..so in total 12 minutes

Glenn

yeh but u cant do that cos u only got 1 flashlight!!!

[Guest]

10 mins...

my answer is as follows :

1) the "10 min guy" (holding the flashlight) start crosseing the bridge with "5 min guy."

2) After 5 mins, when the "5 min guy" crossed the bridge then "2 min guy" start crossing

the bridge (now the "10 min guy" is showing him ("2 min guy") the flashlight on the starting

of the bridge).

3) after 2 more mins, when "2 min guy" will have crossed the bridge, then "1 min guy" start

crossing the bridge (now "10 min guy" is showing the light to "1 min guy")

4) In this way all the conditions (@ a time 2 person should be on the brigde & one

of them must be having flashlight) is fullfilled.

total time spend is 10 mins.

how is it .....

[Guest]

1) the "10 min guy" (holding the flashlight) start crosseing the bridge with "5 min guy."

2) After 5 mins, when the "5 min guy" crossed the bridge

The "5 min guy" can't finish crossing the bridge in five minutes because he's with the "10 min guy".

The riddle states "There's only one flashlight among them, and it is necessary to use the flashlight to see while crossing".

If the 5 minute guy was going at his max speed, the 10 min guy would be too far behind for much of the trip and wouldn't get the necessary benefit of crossing with the flashlight.

[Guest]

but it would be possible tht the "10 min guy" is crossing with his speed and showing the light to "5 min guy" till end ..

now when the "5 min guy" crossed the bridge the "10 min guy" is in the middle ..and he will be able to show them light

(the "2 min guy" and "5 min guy") .....similarly with the "2minguy" & "1 min guy" case ..

now what ??

[Guest]

Answer is 12 minutes

Step 1 : Let the 10 mins guy start crossing...

Step 2 : After 5 minutes, let the 5 minute guy start..they reach the end at the same time

Step3 : Let the 2 minutes guy start

Step 4 : After a minute, let the one minute guy start...they reach at the same time..so in total 12 minutes

Glenn

Remember the flashlight, young grasshopper.

[Guest]

but it would be possible tht the "10 min guy" is crossing with his speed and showing the light to "5 min guy" till end ..

now when the "5 min guy" crossed the bridge the "10 min guy" is in the middle ..and he will be able to show them light

(the "2 min guy" and "5 min guy") .....similarly with the "2minguy" & "1 min guy" case ..

now what ??

There's two problems with this.

1. You are making the assumption that this flashlight is able to be used to see where you're walking, and at the same time allow someone five minutes ahead to see where he's walking.

2. Flashlights are directional. In your solution, when the 10 min guy is five minutes through his trip, the light from the flashlight allows him to see what's ahead of him, and also allows someone five minutes behind him to see what's directly in front of him. Not a reasonable expectation from any flashlight.

[Guest]

I think some people are missing the point.

Two people can be ON the bridge at any point. You can't carry anyone.

When anyone (one or two people) gets on the bridge, they (or at least one of the two people) must be holding the flashlight. You can't throw it or anything. There's no trick involving the flashlight.

When two people cross, they cross at the speed of the slower person. So if Pruden and Moore cross together, it takes 10 minutes.

MSGT Moore: 1 minute

1LT Jackson: 2 minutes

PFC Diggs: 5 minutes

CPT Pruden: 10 minutes

1. Moore and Jackson - 2 min

2. Moore returns with light - 1 min

3. Diggs and Pruden - 10 minutes

4. Jackson returns with light - 2 min

5. Moore and Jackson - 2 min

Total time: 17 minutes

[Guest]

Four soldiers must cross a bridge and they know the enemy is not far behind. Only up to two can safely walk on the bridge at any time. There's only one flashlight among them, and it is necessary to use the flashlight to see while crossing.

The soldiers have various injuries and can only cross the bridge so fast.

The following are the fastest times that each can cross:

MSGT Moore: 1 minute

1LT Jackson: 2 minutes

PFC Diggs: 5 minutes

CPT Pruden: 10 minutes

What is the fastest time they can achieve in all safely crossing the bridge?

You forgot an essentiel part of the puzzle : if two people cross together one has to go back again and together they walk the pace of the slower. Furthermore the bridge will blow up so after a while it is impossible for the last one to return again so you have the shortest possible way

(if one person returns then the third person can start walking

[Guest]

You forgot an essentiel part of the puzzle : if two people cross together one has to go back again and together they walk the pace of the slower.

I didn't forget to mention that as it's not part of the question; it's part of the solution.

Furthermore the bridge will blow up so after a while it is impossible for the last one to return again so you have the shortest possible way

(if one person returns then the third person can start walking

What are you talking about? There's no reason the bridge should blow up and there's no reason it's impossible for the last one to return.

[Guest]

I say 12 min.

The 10 min and 5 min go together with the flashlight and then shine the path for the 2 and 1 min walkers to cross

[Guest]

msgt goes first with cpt taking 10 min

msgt goes back 1 min

gets 1lt brings him/ her over 2 min

msgt goes back 1 min,

gets pfc 5 min.

They are all over the bridge in 19 min.

[Guest]

17 minutes

[Guest]

When I first read this I thought the flash light was non important to cross with the soldiers, if it is nessacary for them to carry the flash light then it adds

If they don't have to carry the flash light, and in true brotherhood of the army, the 2 fast guys should carry the 2 slowest.

I only reached this due to the fact that most of the time you carry some one who might slow you down otherwise.

1. Moore carries Diggs while Jackson or Pruden shine the light on their path for them 1 minute

2. Jackson carries Pruden and brings the flashlight with them. 2 minutes

If they have to take the flash light with, then as follows, still carrying their slow team mates.

1. Moore carries Diggs 1 Minute

2. Moore Returns 1 minute

3. Moore carries Pruden 1 minute

4. Moore returns 1 minute

5. Moore carries Jackson 1 minute

Of course poor Moore will need a browse star after these heroics.

[Superdood]

if msgt moore carries them all at the same time, the time is one minute.