Puzzle : And Escape Story of Robbers Continues

Where story begins?

Babylas, Hilary, and Sosthenes have escaped the tower and divided their treasure into three bags. But now they must cross a river, and the boat can accommodate only two men at a time, or one man and a bag. None will trust another with his bag on the shore, but they agree that a man in the boat can be trusted to drop or retrieve a bag at either shore, as he’ll be too busy to tamper with it.

 How can they cross the river?

Source. 


This is how they can cross the river! 

 

Solution: Robbers' Planned Journey Across the River

Why they need a PLAN?

Let's recall that the boat can accommodate only two men at a time, or one man and a bag.

1. Sosthenes takes his bag across the river leaves it at other shore & comes back.

2. Sosthenes takes Hilari's bag to the other shore & leaves it there where his own bag is already there. 

3. Now, Hilari takes Sosthenes to the other shore, leaves him there & come back after recollecting own bag.

4. Hilari drops own bag at near shore & takes Babylas to other shore & returns back.

5. Next, he takes Babylas's bag & drops it at other shore where Babylas is waiting for his bag. And Hilary returns once again.

6. Finally, he collects his own bag and takes it to other shore.

The River Crossing Challenge!

There are 3 men, two Chimps, and one Gorilla on one side of a river :

• They have a boat but only the men and the Gorilla can row the boat across, so there must always be a human and/or Gorilla on the boat.

• The boat can only carry two people/monkeys.

• If monkeys and humans are together on one side of the river there must be as many or more people than monkeys for the men's safety. 

How can all men and monkeys make it to the other side ? 



Here is the PROCESS by which it can be done! 

Responding to The River Crossing Challenge!

What was the challenge ahead?

Recalling the conditions those need to be followed. 

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• They have a boat but only the men and the Gorilla can row the boat across, so there must always be a human and/or Gorilla on the boat.

• The boat can only carry two people/monkeys.

• If monkeys and humans are together on one side of the river there must be as many or more people than monkeys for the men's safety.

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Here, we go step by step process. (M - Men, G - Gorilla, C - Chimps)

1. The gorilla takes 1 chimp across the river and comes back. 

    (M - 3, G - 1, C - 1 | M - 0, G - 0, C - 1) 

2. Again, gorilla takes 1 man across the river and comes back. 

    (M - 2, G - 1, C - 1 | M - 1, G - 0, C - 1)

Now, here gorilla can't take chimp across the river as that will violate condition 3 on that side. Neither gorilla can take 1 man on other side and return back since number of monkeys on returning side will be more than people again violating condition 3.

3. Next, one man drops gorilla at the other side and bring back chimp.

    (M - 2, G - 0, C - 2 | M - 1, G - 1, C - 0) 

4. Now, 2 men has to cross the river and send back gorilla for the rest of work.

   (M - 0, G - 1, C - 2 | M - 3, G - 0, C - 0) 

5. Finally, gorilla takes 2 chimps across the river in 2 round trips.

   (M - 0, G - 0, C - 0 | M - 3, G - 1, C - 2) 

 

Row Row Row A Tiny RowBoat : Puzzle

Walter, Xavier, Yoshi, and Zeke crossed a river in a tiny rowboat. They all started on the same side of the river. They made three trips from the starting side to the destination side, and two trips from the destination side to the starting side. Here are some facts:

1. On each trip from the starting side of the river to the destination side, two people were in the boat, but only one person rowed the boat, and that person rowed the boat for the entire trip.

2. On each return trip, only one person was in the boat.

3. Walter is the weakest of the group. He could only row the boat if no one else is in it.

4. Xavier is the second weakest of the group. He can only row the boat if he is by himself or if Yoshi, the lightest of the group, is a passenger.

5. Each man rowed the boat at least once. 

Click here for SOLUTION! 

Row Row Row A Tiny RowBoat Puzzle : Solution

What was the puzzle?

We know, Walter, Xavier, Yoshi, and Zeke crossed a river in a tiny rowboat. They all started on the same side of the river. They made three trips from the starting side to the destination side, and two trips from the destination side to the starting side. 

And we have some facts:

1. On each trip from the starting side of the river to the destination side, two people were in the boat, but only one person rowed the boat, and that person rowed the boat for the entire trip.

2. On each return trip, only one person was in the boat.

3. Walter is the weakest of the group. He could only row the boat if no one else is in it.

4. Xavier is the second weakest of the group. He can only row the boat if he is by himself or if Yoshi, the lightest of the group, is a passenger.

5. Each man rowed the boat at least once. 

ANALYSIS :

1] Walter must not had rowed from start to the destination since he is weakest among as per FACT 3. Since, he had to row at least once as per FACT 5, he must had rowed a return tip.


2] The person who had rowed twice, must not had both trips from start to destination. That's because, in that case, he would have had needed third trip in form of return trip to get back to the start once again. So, he must had rowed a return trip at least once.

3] Suppose Walter is the person who rowed the boat twice. Both of his trips must be return trips as concluded in [1] above. 

So if Walter had rowed 2 return trips then each of Xavier, Yoshi and Zeke must have rowed 1 trip from start to the destination. 

If Walter had 'taken' Zeke (while Zeke rowing) across and returned then he would have had to 'take' Yoshi (while Yoshi rowing) across as Xavier being unable to row Walter as per FACT 4. And on returning back to the start after leaving Yoshi across, Walter and Xavier would have had been at the starting point. Now, Walter being unable to row with passenger & Xavier being unable to row Walter, both would have had stuck at the start point.

In short, Walter is not the person for sure who had rowed twice.

4] We know, Walter had one return trip. So the other return trip must have been rowed by someone among Xavier, Yoshi or Zeke. Moreover, the rest of three trips from start to the destination must have rowed by Xavier, Yoshi and Zeke in some order. 

That's how, the one person among Xavier, Yoshi and Zeke, must have rowed twice, one trip from source to destination and other one return trip.

5] If Xavier had rowed twice, then with one trip he must have taken Yoshi across and in other trip he must have returned as we found the fact in [2] above. So, two return trips 'occupied' by Walter and Xavier, Yoshi wouldn't have got a chance to row which is mandatory.

So, Xavier is not the person who had rowed twice.

6] Suppose Zeke is the person who had rowed twice. He must had rowed Walter across the river to give a chance to row his return trip. After Walter reaching at the start, Xavier must had rowed Yoshi across the river thereby completing his compulsory rowing trip.

Then Zeke must have returned to the start to take Walter across then Yoshi would have been the person who hadn't rowed which is against FACT 5.

Therefore, Zeke must not be the person who rowed twice.

7] So, Yoshi must be the person who rowed twice. 

POSSIBILITY 1 : Zeke took Walter across to give him row trip in return. Then, Xavier rowed Yoshi across and Yoshi returned back to take Walter across.

POSSIBILITY 2 : First Xavier rowed Yoshi across and Yoshi returned back after which Zeke takes Walter across to allow Walter to have return trip, and finally, Yoshi taking Walter across the river.

POSSIBILITY 3 : Yoshi took Walter across the river and Walter returned. Zeke rowed Walter across and Yoshi returned to give Xavier a chance to row him across.

An Island Of Puzzles

There is an Island of puzzles where numbers 1 - 9 want to cross the river.

There is a single boat that can take numbers from one side to the other.

However, maximum 3 numbers can go at a time and of course, the boat cannot sail on its own so one number must come back after reaching to another side.

Also, the sum of numbers crossing at a time must be a square number.

You need to plan trips such that minimum trips are needed.

This should be that minimum number! 

Numbers On An Island Of Puzzles

What was the challenge?

We need only 7 trips to send all digits across the river.

1. Send 2, 5, 9 (sum is 16).

2. Bring back the 9.

3. Send 3,4, 9 (sum is 16).

4. Bring back the 9.

5. Now send 1,7,8 (sum is 16).

6. Bring back the 1.

7. And finally send 1,6,9 (sum is 16).

Clues From Talk About Boats

At the local model boat club, four friends were talking about their boats. There were a total of eight boats, two in each color, red, green, blue and yellow. 

1. Each friend owned two boats. 

2. No friend had two boats of the same color.

3. Alan didn't have a yellow boat.

4. Brian didn't have a red boat, but did have a green one.

5. One of the friends had a yellow boat and a blue boat and another friend had a green boat and a blue boat. 

6. Charles had a yellow boat. 

7. Darren had a blue boat, but didn't have a green one.

Can you work out which friend had which colored boats? 

Know here step by step process of finding owners! 

Source 

Owners Of Boats

What's the task given? 

First let's rewrite all the clues here.

1. Each friend owned two boats. 

2. No friend had two boats of the same color.

3. Alan didn't have a yellow boat.

4. Brian didn't have a red boat, but did have a green one.

5. One of the friends had a yellow boat and a blue boat and another friend had a green boat and a blue boat. 

6. Charles had a yellow boat. 

7. Darren had a blue boat, but didn't have a green one.

Let's make 2 set of 4 colors of boats. Below is the table with owners in row & color of boats in columns.  

Below are clues which giving clear idea of owner of particular colored boat.

3. Alan didn't have a yellow boat.

4. Brian didn't have a red boat, but did have a green one.

6. Charles had a yellow boat.

7. Darren had a blue boat, but didn't have a green one.

We will fill this table one by one as per clues given.

Now, consider the first part of this clue.

5. One of the friends had a yellow boat and a blue boat.

Now Alan won't have this combination as he doesn't own yellow boat at all. The Brian already had green boat, so he too can't have this combination as in that case he would own 3 boats.

Let's assume Charles had this combination then other would have boats as below.

250 Lbs Across The River?

Two boys weighing 50 pounds each and their older brother weighing 100 pounds wish to cross a river. Their boat will only hold 100 pounds.

How can they all cross the river in the boat?

Find here how they can! 

Source 

Taking 250 Lbs Across The River.

What was the challenge? 

1. First 2 boys of 50 pounds should cross the river.

2. One of them should bring back the boat at other end.

3. A boy with 100 pounds should carry himself across the river with boat.

4. Other boy of 50 pounds waiting across the river now should bring back the boat again.

5. Now both boys of 50 pounds now should cross the river.