Under The Cup Riddle
You decide to play a game with your friend where your friend places a coin under one of three cups. Your friend would then switch the positions of two of the cups several times so that the coin under one of the cups moves with the cup it is under. You would then select the cup that you think the coin is under. If you won, you would receive the coin, but if you lost, you would have to pay.
As the game starts, you realise that you are really tired, and you don't focus very well on the moving of the cups. When your friend stops moving the cups and asks you where the coin is, you only remember a few things:
He put the coin in the rightmost cup at the start.
He switched two of the cups 3 times.
The first time he switched two of the cups, the rightmost one was switched with another.
The second time he switched two of the cups, the rightmost one was not touched.
The third and last time he switched two of the cups, the rightmost one was switched with another.
You don't want to end up paying your friend, so, using your head, you try to work out which cup is most likely to hold the coin, using the information you remember.
Which cup is most likely to hold the coin?
As the game starts, you realise that you are really tired, and you don't focus very well on the moving of the cups. When your friend stops moving the cups and asks you where the coin is, you only remember a few things:
He put the coin in the rightmost cup at the start.
He switched two of the cups 3 times.
The first time he switched two of the cups, the rightmost one was switched with another.
The second time he switched two of the cups, the rightmost one was not touched.
The third and last time he switched two of the cups, the rightmost one was switched with another.
You don't want to end up paying your friend, so, using your head, you try to work out which cup is most likely to hold the coin, using the information you remember.
Which cup is most likely to hold the coin?
Hint: Write down the possibilities. Remember that there are only three cups, so if the rightmost cup wasn't touched...
The rightmost cup.
The rightmost cup has a half chance of holding the coin, and the other cups have a quarter chance.
Pretend that Os represent cups, and Q represents the cup with the coin.
The game starts like this:
OOQ
Then your friend switches the rightmost cup with another, giving two possibilities, with equal chance:
OQO
QOO
Your friend then moves the cups again, but doesn't touch the rightmost cup. The only switch possible is with the leftmost cup and the middle cup. This gives two possibilities with equal chance:
QOO
OQO
Lastly, your friend switches the rightmost cup with another cup. If the first possibility shown above was true, there would be two possibilities, with equal chance:
OOQ
QOO
If the second possibility shown above (In the second switch) was true, there would be two possibilities with equal chance:
OOQ
OQO
This means there are four possibilities altogether, with equal chance:
OOQ
QOO
OOQ
OQO
This means each possibility equals to a quarter chance, and because there are two possibilities with the rightmost cup having the coin, there is a half chance that the coin is there. Did you answer this riddle correctly?
YES NO
The rightmost cup has a half chance of holding the coin, and the other cups have a quarter chance.
Pretend that Os represent cups, and Q represents the cup with the coin.
The game starts like this:
OOQ
Then your friend switches the rightmost cup with another, giving two possibilities, with equal chance:
OQO
QOO
Your friend then moves the cups again, but doesn't touch the rightmost cup. The only switch possible is with the leftmost cup and the middle cup. This gives two possibilities with equal chance:
QOO
OQO
Lastly, your friend switches the rightmost cup with another cup. If the first possibility shown above was true, there would be two possibilities, with equal chance:
OOQ
QOO
If the second possibility shown above (In the second switch) was true, there would be two possibilities with equal chance:
OOQ
OQO
This means there are four possibilities altogether, with equal chance:
OOQ
QOO
OOQ
OQO
This means each possibility equals to a quarter chance, and because there are two possibilities with the rightmost cup having the coin, there is a half chance that the coin is there. Did you answer this riddle correctly?
YES NO
Dropping Coconuts Riddle
You have two coconuts and you want to find out how high they can be dropped from a 100 story building before they break. But you only have $1.40 and the elevator costs a dime each time you ride it up (it's free for rides down).
How can you drop the coconuts to guarantee you will find the lowest floor they will break at, while starting and ending at floor 1?
How can you drop the coconuts to guarantee you will find the lowest floor they will break at, while starting and ending at floor 1?
Hint: They break when dropped from the same height and they don't weaken from getting dropped.
You could drop it at floor 1 first (because you start at floor 1). Then you would go to the floors: 14, 27, 39, 50, 60, 69, 77, 84, 90, 95, 99, and 100. Whatever floor your first coconut breaks at, go to the floor above the last floor the coconut survived and drop the second coconut from this floor. Then go up by one floor until the second coconut breaks and that is the lowest floor it will break at. Did you answer this riddle correctly?
YES NO
YES NO
Coconut Sentence Riddle
Hint: Listen closely...
This.
If 'this' is a coconut, and 'that' is a coconut, then 'is' 'this' a coconut. Did you answer this riddle correctly?
YES NO
If 'this' is a coconut, and 'that' is a coconut, then 'is' 'this' a coconut. Did you answer this riddle correctly?
YES NO
The Weight Of A Melon Riddle
Hint: We are to determine X the total mass of melon after the drying.
The Dry weight, DW is 1lb both before and after the drying.
The New Water weight, WNW is clearly X - DW or X - 1
Ducks On Ducks
There are 2 ducks in front of 2 other ducks.
There are 2 ducks behind 2 other ducks.
There are 2 ducks beside 2 other ducks.
How many ducks are there?
There are 2 ducks behind 2 other ducks.
There are 2 ducks beside 2 other ducks.
How many ducks are there?
Hint:
Almost Blind Riddle
Without a bridle, or a saddle, across a thing I ride a-straddle. And those I ride, by help of me, though almost blind, are made to see.
What am I?
What am I?
Hint:
Give Me Food And I Will Live Give Me Water And I Will Die
Hint:
Prince Age Riddle
What are their ages?
Hint:
Current Future Past
Princess x 2z (x+y)/2
Prince y x z
I then created three equations, since the difference in their age will always be the same.
d = the difference in ages
x y = d
2z x = d
x/2 + y/2 z = d
I then created a matrix and solved it using row reduction.
x y z
1 -1 0 d
-1 0 2 d
.5 .5 -1 d
It reduced to:
x y z
1 0 0 4d
0 1 0 3d
0 0 1 5d/2
This means that you can pick any difference you want (an even one presumably because you want integer ages).
Princess age: 4d
Prince age: 3d
Ages that work
Princess:
4
8
16
24
32
40
48
56
64
72
80
Prince:
3
6
12
18
24
30
36
42
48
54
60 Did you answer this riddle correctly?
YES NO
Princess x 2z (x+y)/2
Prince y x z
I then created three equations, since the difference in their age will always be the same.
d = the difference in ages
x y = d
2z x = d
x/2 + y/2 z = d
I then created a matrix and solved it using row reduction.
x y z
1 -1 0 d
-1 0 2 d
.5 .5 -1 d
It reduced to:
x y z
1 0 0 4d
0 1 0 3d
0 0 1 5d/2
This means that you can pick any difference you want (an even one presumably because you want integer ages).
Princess age: 4d
Prince age: 3d
Ages that work
Princess:
4
8
16
24
32
40
48
56
64
72
80
Prince:
3
6
12
18
24
30
36
42
48
54
60 Did you answer this riddle correctly?
YES NO
Missing Dollar Riddle
Hint: Make a list of all of the people involved and how much money they ended up with/spent.
The $9 paid by each guest accounts for the $2 that went to the bellhop. So rather than adding $27 to the $2 kept by the bellhop, the $27 accounts for the bellhops money. The $27 plus the $3 kept by the guests does add up to $30. Did you answer this riddle correctly?
YES NO
YES NO
Rope Burn Riddle
Hint: You can light multiple ends and/or multiple ropes at the exact same time.
Light both ends of one rope, and only one end of the other rope. This will cause the first rope to burn out in 30 minutes. When the first rope burns out, there will be 30 minutes left on the second rope. So then, light the other end of the second rope, and the rest of it will burn out in 15 minutes. 30 + 15 = 45 minutes. Did you answer this riddle correctly?
YES NO
YES NO
Intertwining Dimensions Riddle
More than just a double triangle, I intertwine the internal and external dimensions of God, Torah and Israel. What am I?
Hint:
What Comes Next Riddle
Hint:
E. Each item is the first letter(s) of one of the seven continents:
1. Asia
2. North America
3. Africa
4. South America
5. Australia
6. Antarctica
7. Europe Did you answer this riddle correctly?
YES NO
1. Asia
2. North America
3. Africa
4. South America
5. Australia
6. Antarctica
7. Europe Did you answer this riddle correctly?
YES NO
I Smash Others Riddle
I tell you when to start,
Or remind if you forget.
I smash others to break them apart,
But Im pushed by another of me.
What am I?
Or remind if you forget.
I smash others to break them apart,
But Im pushed by another of me.
What am I?
Hint:
Cue. A cue tells you when to start, or if you forget your lines in a play. A cue ball is used to break at the beginning of a game of pool and the cue stick is used to push the cue ball on the break. Did you answer this riddle correctly?
YES NO
YES NO
Moving Quarters Riddle
Hint:
Hold down one of the quarters very firmly. Take another coin and hit it against the quarter you are holding down. Tap hard enough to move the quarter next to it aside. Did you answer this riddle correctly?
YES NO
YES NO
When I Turn Around Riddle
When I turn around once. What is out will not get in. When I turn around again. What is in will not get out. What might I be?
Hint:
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