maths based riddles... See if you can answer them.
Discussion
I'll try and keep this one alive for a bit - again with a logic puzzle rather than mathematics.
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
Du1point8 said:
So many maths based riddles that I thought I would start a new thread for them all as a little game were the person who answers with the correct answer gets to ask the next one...
I had some fun confusing my friends last night with this little one that they couldnt get their head round.
If you have a one mile race track and you must complete two laps, for a total of two miles.
no more, no less.
If you average 30mph on the first one mile lap, how fast would you have to go on the second lap to average 60 MPH?
I await the first smart arsed comment.
The question can be read to imply that the mean speed required (60 mph in this case) must be done over two laps. In which case, since at 30 mph it has already taken 2 minutes to complete one lap, there is no time left to complete another lap - at any speed.I had some fun confusing my friends last night with this little one that they couldnt get their head round.
If you have a one mile race track and you must complete two laps, for a total of two miles.
no more, no less.
If you average 30mph on the first one mile lap, how fast would you have to go on the second lap to average 60 MPH?
I await the first smart arsed comment.
If the mean speed is to be calculated on a lap by lap basis, then the answer is 60 mph for the second lap.
Einion Yrth said:
I'll try and keep this one alive for a bit - again with a logic puzzle rather than mathematics.
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
What's my name?You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
The answer to the second question is -
Ask one guard what the other guard would advise, i.e. which door leads to escape.
If the guard you ask is the truthfull guard, he knows the other guard (the liar) will advise you wrongly, and will point you to the wrong door (door to death).
If the guard you ask is the liar, he knows the other guard (the truthfull guard) will advise you correctly, and will lie to you and advise you to open the wrong door (door to death).
So in both cases you don't open the door which you're advised to, and open the other instead.
Ask one guard what the other guard would advise, i.e. which door leads to escape.
If the guard you ask is the truthfull guard, he knows the other guard (the liar) will advise you wrongly, and will point you to the wrong door (door to death).
If the guard you ask is the liar, he knows the other guard (the truthfull guard) will advise you correctly, and will lie to you and advise you to open the wrong door (door to death).
So in both cases you don't open the door which you're advised to, and open the other instead.
Du1point8 said:
Easier to place back than a square one.
One man can move a round one by rolling it.
H & S as there are not sharp edges?
What about man-holes on hills. I'd have thought a large heavy circular man-hole rolling down a long hill had potential for devastation.One man can move a round one by rolling it.
H & S as there are not sharp edges?
Crickey, they must be about 20 Kgs a pop I'd think.
Einion Yrth said:
I'll try and keep this one alive for a bit - again with a logic puzzle rather than mathematics.
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
How about "are you a guard" if he answers no use the other door, if he answers yes, use this one.You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
Einion Yrth said:
I'll try and keep this one alive for a bit - again with a logic puzzle rather than mathematics.
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
Been watching Labyrinth?You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
samdale said:
Einion Yrth said:
I'll try and keep this one alive for a bit - again with a logic puzzle rather than mathematics.
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
Been watching Labyrinth?You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
Einion Yrth said:
samdale said:
Einion Yrth said:
I'll try and keep this one alive for a bit - again with a logic puzzle rather than mathematics.
You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
Been watching Labyrinth?You are trapped in a room with two guarded doors; one door leads to certain death, the other to escape. One of the guards always tells the truth, the guard of the other door always lies. You are permitted to ask one question of either, but not both, of the guards. What question will ensure that you exit through the safe door?
dvance said:
A similar one is: You're at a TV show where you're faced with three doors. There are two goats and an MX-5 behind them. Your task is to choose the door behind which the ultimate driving machine is placed. You choose a door, but then the TV host opens up one of the remaining doors to reveal a goat. The question now is what is the best strategy (the one that maximizes your chances of winning) -- to keep your choice or switch your chosen door?
The 'Monty Hall' problem causes as much heightened argument as the plane and conveyor belt one. Mathematically you have a better chance if you switch your choice because the door that has been opened is always to reveal a goat, it is not at random. Therefore you are being offered the choice between your original door and 'both of the other doors'.Einion Yrth said:
The 'Monty Hall' problem causes as much heightened argument as the plane and conveyor belt one. Mathematically you have a better chance if you switch your choice because the door that has been opened is always to reveal a goat, it is not at random. Therefore you are being offered the choice between your original door and 'both of the other doors'.
Correct 
I should have posted a less famous question 
My turn, my turn !!!
OK, you've got two balls (fnar fnar), both weigh and look the same, one is made of a dense material and is hollow, whereas the other is made from a less dense naterial and is solid.
You roll them both down a track - which one goes faster and why ?
Remember, no googling the answer (if you do your soul will burn in hell for eternity).
OK, you've got two balls (fnar fnar), both weigh and look the same, one is made of a dense material and is hollow, whereas the other is made from a less dense naterial and is solid.
You roll them both down a track - which one goes faster and why ?
Remember, no googling the answer (if you do your soul will burn in hell for eternity).
dvance said:
A similar one is: You're at a TV show where you're faced with three doors. There are two goats and an MX-5 behind them. Your task is to choose the door behind which the ultimate driving machine is placed. You choose a door, but then the TV host opens up one of the remaining doors to reveal a goat. The question now is what is the best strategy (the one that maximizes your chances of winning) -- to keep your choice or switch your chosen door?
been watching the film 21 have we?911newbie said:
My turn, my turn !!!
OK, you've got two balls (fnar fnar), both weigh and look the same, one is made of a dense material and is hollow, whereas the other is made from a less dense naterial and is solid.
You roll them both down a track - which one goes faster and why ?
Remember, no googling the answer (if you do your soul will burn in hell for eternity).
Good one! Is it because the dense, hollow ball, because it has more of its weight at greater distance from the center of rotation, giving greater momentum?OK, you've got two balls (fnar fnar), both weigh and look the same, one is made of a dense material and is hollow, whereas the other is made from a less dense naterial and is solid.
You roll them both down a track - which one goes faster and why ?
Remember, no googling the answer (if you do your soul will burn in hell for eternity).
(This is an uneducated guess, but you never know.)
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