Various riddles.

This was posted a while back. So here it is again .

----A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a conclusion can be logically deduced, they will do it instantly. No one knows the color of their eyes. Every night at midnight, a ferry stops at the island. Any islanders who have figured out the color of their own eyes then leave the island, and the rest stay. Everyone can see everyone else at all times and keeps a count of the number of people they see with each eye color (excluding themselves), but they cannot otherwise communicate. Everyone on the island knows all the rules in this paragraph.

On this island there are 100 blue-eyed people, 100 brown-eyed people, and the Guru (she happens to have green eyes). So any given blue-eyed person can see 100 people with brown eyes and 99 people with blue eyes (and one with green), but that does not tell him his own eye color; as far as he knows the totals could be 101 brown and 99 blue. Or 100 brown, 99 blue, and he could have red eyes.

The Guru is allowed to speak once, on one day in all their endless years on the island. Standing before the islanders, she says the following: "I can see someone with brown eyes"

Who gets to leave , and on what night?

Can multiple people leave on one day?ryrulez

By doing as little thinking as possible and simply using numbers provided and logic of absolutes I will say that everyone but the guru leaves after 100 days.FragStains

Most definately wrong but,

They would all have guessed years ago because on the first night they could have all said "I have blue eyes" those that did, would go and the rest would have eliminated the fact that their eyes are blue. Then by powers of deduction would be able to keep guessing their own eye colours pretty quickly. They would all heve been gone within a week.

Maybe this is not in the spirit of the riddle. He he

Most definately wrong but,

They would all have guessed years ago because on the first night they could have all said "I have blue eyes" those that did, would go and the rest would have eliminated the fact that their eyes are blue. Then by powers of deduction would be able to keep guessing their own eye colours pretty quickly. They would all heve been gone within a week.

Maybe this is not in the spirit of the riddle. He he

Gardenpath

That would be correct. Can you explain why this is so and why the announcement was needed? dave123321

[QUOTE="dave123321"]That would be correct. Can you explain why this is so and why the announcement was needed? markop2003

[QUOTE="Gardenpath"]

Most definately wrong but,

They would all have guessed years ago because on the first night they could have all said "I have blue eyes" those that did, would go and the rest would have eliminated the fact that their eyes are blue. Then by powers of deduction would be able to keep guessing their own eye colours pretty quickly. They would all heve been gone within a week.

Maybe this is not in the spirit of the riddle. He he

dave123321

[QUOTE="markop2003"][QUOTE="dave123321"]That would be correct. Can you explain why this is so and why the announcement was needed? dave123321

I'm not sure I got the riddle... there are 201 people on the island right? 100 Brown, 100 blue, and 1 green. Do the islanders know about this info or not? I was confused about the red eyed part...and does the guru speak only once or only once a day?nintendo-4life

[QUOTE="dave123321"][QUOTE="Gardenpath"]

Most definately wrong but,

They would all have guessed years ago because on the first night they could have all said "I have blue eyes" those that did, would go and the rest would have eliminated the fact that their eyes are blue. Then by powers of deduction would be able to keep guessing their own eye colours pretty quickly. They would all heve been gone within a week.

Maybe this is not in the spirit of the riddle. He he

markop2003

can these people guess or is trial-and-error prohibited?nintendo-4life

[QUOTE="nintendo-4life"]can these people guess or is trial-and-error prohibited?dave123321

This was posted a while back. So here it is again .

----A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a conclusion can be logically deduced, they will do it instantly. No one knows the color of their eyes. Every night at midnight, a ferry stops at the island. Any islanders who have figured out the color of their own eyes then leave the island, and the rest stay. Everyone can see everyone else at all times and keeps a count of the number of people they see with each eye color (excluding themselves), but they cannot otherwise communicate. Everyone on the island knows all the rules in this paragraph.

On this island there are 100 blue-eyed people, 100 brown-eyed people, and the Guru (she happens to have green eyes). So any given blue-eyed person can see 100 people with brown eyes and 99 people with blue eyes (and one with green), but that does not tell him his own eye color; as far as he knows the totals could be 101 brown and 99 blue. Or 100 brown, 99 blue, and he could have red eyes.

The Guru is allowed to speak once, on one day in all their endless years on the island. Standing before the islanders, she says the following: "I can see someone with brown eyes"

Who gets to leave , and on what night?

dave123321

One brown-eyed person can leave once a day for 100 days. Every brown-eyed man can see 99 other brown-eyed men but can't see their own eye color. Yet, they can see 100 blue-eyed men and one green-eyed guru. By this logic, that one man concludes that he has brown eyes and leaves the island. This is repeated until all the brown-eyed men are gone after 100 days.

Theokhoth

[QUOTE="dave123321"]

This was posted a while back. So here it is again .

----A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a conclusion can be logically deduced, they will do it instantly. No one knows the color of their eyes. Every night at midnight, a ferry stops at the island. Any islanders who have figured out the color of their own eyes then leave the island, and the rest stay. Everyone can see everyone else at all times and keeps a count of the number of people they see with each eye color (excluding themselves), but they cannot otherwise communicate. Everyone on the island knows all the rules in this paragraph.

On this island there are 100 blue-eyed people, 100 brown-eyed people, and the Guru (she happens to have green eyes). So any given blue-eyed person can see 100 people with brown eyes and 99 people with blue eyes (and one with green), but that does not tell him his own eye color; as far as he knows the totals could be 101 brown and 99 blue. Or 100 brown, 99 blue, and he could have red eyes.

The Guru is allowed to speak once, on one day in all their endless years on the island. Standing before the islanders, she says the following: "I can see someone with brown eyes"

Who gets to leave , and on what night?

Theokhoth

[QUOTE="Theokhoth"]

One brown-eyed person can leave once a day for 100 days. Every brown-eyed man can see 99 other brown-eyed men but can't see their own eye color. Yet, they can see 100 blue-eyed men and one green-eyed guru. By this logic, that one man concludes that he has brown eyes and leaves the island. This is repeated until all the brown-eyed men are gone after 100 days.

dave123321

[QUOTE="dave123321"]

[QUOTE="Theokhoth"]

One brown-eyed person can leave once a day for 100 days. Every brown-eyed man can see 99 other brown-eyed men but can't see their own eye color. Yet, they can see 100 blue-eyed men and one green-eyed guru. By this logic, that one man concludes that he has brown eyes and leaves the island. This is repeated until all the brown-eyed men are gone after 100 days.

Theokhoth

[QUOTE="dave123321"][QUOTE="Theokhoth"] Let's say that there are only two men on the island with brown eyes, and the other 198 men have blue eyes. When the guru speaks, all 200 men will know that at least one man on the island has brown eyes. Now, the two brown-eyed men will be able to see the brown eyes of the other brown-eyed man, but not their own. When they see that the one man with brown eyes is not leaving the island after a day, he realizes that the man does not know his own eye color either. If there are two men with brown eyes, they would have left on Day 2 after the announcement. If the first man with brown eyes did not leave, then he must see someone else with brown eyes: the second man, who then leaves. This is repeated again and again until all 100 brown-eyed men leave the island.Imperial__Guard

[QUOTE="Theokhoth"][QUOTE="dave123321"] Why does he conclude that he has brown eyes? You are on the right track though.

dave123321

There are 200 men on the island. One of them, a brown-eyed man, can see 99 other brown-eyed men. The same goes for the rest of the brown-eyed men. Since they don't know their own eye color, they watch and wait for all the other brown-eyed men to go. When they do not, they all conclude that they all must see another man with brown eyes, and since all the other people are blue-eyed, the only conclusion must be himself. They all reach this conclusion at the same time, so they all leave on the 100th day.

There are 200 men on the island. One of them, a brown-eyed man, can see 99 other brown-eyed men. The same goes for the rest of the brown-eyed men. Since they don't know their own eye color, they watch and wait for all the other brown-eyed men to go. When they do not, they all conclude that they all must see another man with brown eyes, and since all the other people are blue-eyed, the only conclusion must be himself. They all reach this conclusion at the same time, so they all leave on the 100th day.Theokhoth

[QUOTE="Theokhoth"]There are 200 men on the island. One of them, a brown-eyed man, can see 99 other brown-eyed men. The same goes for the rest of the brown-eyed men. Since they don't know their own eye color, they watch and wait for all the other brown-eyed men to go. When they do not, they all conclude that they all must see another man with brown eyes, and since all the other people are blue-eyed, the only conclusion must be himself. They all reach this conclusion at the same time, so they all leave on the 100th day.dave123321

There are 200 men on the island. One of them, a brown-eyed man, can see 99 other brown-eyed men. The same goes for the rest of the brown-eyed men. Since they don't know their own eye color, they watch and wait for all the other brown-eyed men to go. When they do not, they all conclude that they all must see another man with brown eyes, and since all the other people are blue-eyed, the only conclusion must be himself. They all reach this conclusion at the same time, so they all leave on the 100th day.

Theokhoth

ok, I understand what you are saying, and I see how it would work with 2 brown-eyed men, but how would it work with 100?
Everyday there is 100 brown-eyed men, so what makes that man think one man is looking at him instead of the other 98 men?
Of course, they are going to conclude that they see another another man with brown eyes, since he sees 99, he expects everyone else to at least see 98.

ok, I understand what you are saying, and I see how it would work with 2 brown-eyed men, but how would it work with 100?
Everyday there is 100 brown-eyed men, so what makes that man think one man is looking at him instead of the other 98 men?
Of course, they are going to conclude that they see another another man with brown eyes, since he sees 99, he expects everyone else to at least see 98.

rikkustrife

:?

Here is an easy riddle:

4 - - - 21

7 - - - 36

11 - - - 56

16 - - - ?

What number should go with the question mark?

Here is an easy riddle:

4 - - - 21

7 - - - 36

11 - - - 56

16 - - - ?

What number should go with the question mark?

dave123321

Another one :

"During a seven-day period from Sunday through Saturday, Eliza Pseudonym has dined at seven different local restaurants (including Idoaho Fried Chicken) twice each: once for lunch, and once on a different day for dinner. Each restaurant is located on a different street (from 1st through 7th). Using the following clues, determine where each restaurant is located, and which restaurant Eliza ate at for lunch and for dinner each day. Note: the clues only refer to lunches and dinners during the seven-day period.

Clue 1: Wednesday was the only day on which Eliza ate at two restaurants on consecutively numbered streets.

Clue 2: Eliza had lunch at the restaurant located on the 6th Street on Monday.

Clue 3: Eliza ate at Chick-Empty-A on Tuesday and Friday.

Clue 4: Eliza ate at Long John Bronze's on two consecutive days.

Clue 5: Eliza ate her lunch at the 1st Street restaurant precisely three days after she ate her dinner at the 5th Street restaurant.

Clue 6: On Sunday, Eliza did not have the restaurant on 4th Street for lunch, nor did she eat at Waffle Habitat for dinner.

Clue 7: On one paticular day, Eliza ate at Dice's Pizza (located on an odd numbered street) and Taco Marimba, in some order.

Clue 8: During the three-day period from Sunday through Tuesday, Eliza had eaten something at all seven restaurants excluding the one located on 7th Street; during the three-day period from Thursday through Saturday, Eliza had eaten something at all seven restaurants excluding Questionnos."

[QUOTE="dave123321"]

Here is an easy riddle:

4 - - - 21

7 - - - 36

11 - - - 56

16 - - - ?

What number should go with the question mark?

Theokhoth

[QUOTE="Theokhoth"]

[QUOTE="dave123321"]

Here is an easy riddle:

4 - - - 21

7 - - - 36

11 - - - 56

16 - - - ?

What number should go with the question mark?

dave123321

I got it? :o HUZZAH!

[QUOTE="dave123321"][QUOTE="Theokhoth"] I never figured out how to solve these. :? I'll say 81.

Theokhoth

I got it? :o HUZZAH!

[QUOTE="Theokhoth"]

[QUOTE="dave123321"] Correct. dave123321

I got it? :o HUZZAH!

That's not how I figured it out though. >.>

And another : 9, 61, 52, 63, 94, ___ , 18 dave123321

That's not how I figured it out though. >.>

Theokhoth

[QUOTE="dave123321"]And another : 9, 61, 52, 63, 94, ___ , 18 Theokhoth

How did you?

Each number on the right column is a multiple of five higher than the number above it. Each new column adds five more, so I just followed that to its conclusion.

Nope. How did you go about getting this ?

Damn it. :x Same basic logic: the ones place appears to have a pattern: 9, 6, 5, 6, 9. The tens place definitely has a pattern: 1, 2, 3, 4, 5, 6. . . . .again, I just followed it to what I thought was the right step in the pattern.

How did you?

Each number on the right column is a multiple of five higher than the number above it. Each new column adds five more, so I just followed that to its conclusion.

Nope. How did you go about getting this ?

Damn it. :x Same basic logic: the ones place appears to have a pattern: 9, 6, 5, 6, 9. The tens place definitely has a pattern: 1, 2, 3, 4, 5, 6. . . . .again, I just followed it to what I thought was the right step in the pattern.

Theokhoth

Edit: looking back your solution does not seem to fit. The ones place is 9,1,2,3,4,-,8

10's are x,6,5,6,9,-,1

There appears to be no clear pattern when looking at it as a whole.