| Author | Primary school questions |
|---|
u how to kill a dead hero?
(lordwm answer) |
#51
That is the common wrong reasoning.
I agree that initially, all 3 doors have 1/3 chance of having prize.
You pick a door. Let's call it Door A.
All doors still have a 1/3 chance of the prize.
Now, one of the doors was opened to show you nothing.
As agreed previously, there is equal chances for Door A, Door B, and Door C to contain the prize.
Scenario 1 - The door you pick (Door A) contains the prize
It does not matter which door the game master picks to open as it will be empty.
Scenario 2 - The door you did not pick (Door B) contains the prize
The game master would then be forced to show you the contents of Door C in order to show you nothing.
Scenario 3 - The door you did not pick (Door C) contains the prize
The game master would then be forced to show you the contents of Door B in order to show you nothing.
Out of these 3 scenarios each of equal probability, only 1 of them results in the door you pick containing the prize, while 2 of them results in the door you did not pick contains the prize.
Therefore the door you did not pick has a 2/3 chance of having the prize, and thus better to switch. |
Its not a question related to maths but ur knowledge
u have got 3 switches n u have a bulb in next room u get a chance to " on only one switch " n u have to guess the right switch which lights the bulb.
Now here's the question:which switch should be on to get the possible answer?
(Clue:Bulb gets heated in 5 minutes after lighting up) |
A balloon with volume of 50% the volume of a cube with a 5cm side expands at the rate of 0.1% per minute for half an hour, then the volume decreases at a rate of 0.2% of the new volume for 3 hours. Another balloon has its volume increased from an initial 10cm3 to 45cm3 in 25mins.
Question:
What is the final volume of the first balloon?
What is the rate of change of volume of the second balloon?
What is the percentage of density of the first balloon compared to the second balloon if both balloons are of equal mass?
Note: I do not know the answers, since I'm doing the questions from a hotel room away from my calculators and notes. Just made the questions up from my knowledge of secondary level Additional Mathematics. Enjoy :) |
| Some primary school you went to arcanyx! |
#64
question 1 is 6.75cm³ i think xD |
#62 Sorry, but that's the worst reasoning I've ever seen. Scenario 2 and Scenario 3 are exactly the same.
Initialy, all 3 doors have the same change of having the prize. And that chance is 1/3.
You pick a door, it doesn't matter wich one has the prize, it doesn't matter if you picked right or wrong. All that matters is that he opens a door and show you it has no prize. Now reason a little. What happened? You now have a door with exactly 0 chances of having the prize and two doors that can have the prize. What makes one of these doors has more chances then the other? |
| Actually the reasoning from #62 is completely right, though hard to get your head around it. Look it up on the net. |
#67
Let's say you picked door A. Door B is then shown to you to be empty. And you are then given the chance to either switch to door C or stick with your original choice. Door C now has 2/3 chance because it includes the potential 1/3 chance from door B as well.
The first door you picked will always have 1/3 chance. But the door you are offered will become 2/3 because the game master will always open the empty door. This would be different if the game master opened one of the remaining doors at random. |
for arcanyx:
your question idea is simple but i don`t really understand written data and in english
also then the volume decreases at a rate of 0.2% of the new volume for 3 hours does it mean 0.2% per minute or 0.2% during the whole 3 hours? |
#69 Either I'm too dumb or we aren't talking the same language.
Suppose there are 3 doors: Door A, Door B and Door C. Let's say Door A has the prize. Suppose two people, me and you, play this game separately.
Scenario 1
I choose Door A. You choose Door A.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I win the prize.
You change your choise. You lose the prize.
Scenario 2
I choose Door A. You choose Door B.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I win the prize.
You change your choise, you win the prize.
Scenario 3
I choose Door A. You choose Door C.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I win the prize.
You change your choise, you win the prize.
Scenario 4
I choose Door B. You choose Door A.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I lose the prize.
You change your choise, you lose the prize.
Scenario 5
I choose Door B. You choose Door B.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I lose the prize.
You change your choise, you win the prize.
Scenario 6
I choose Door B. You choose Door C.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I lose the prize.
You change your choise, you win the prize. |
Sorry I haven't finished, missclicked ctrl+enter while writing the message.
Writing the rest now... hang on. |
Scenario 7
I choose Door C. You choose Door A.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I lose the prize.
You change your choise, you lose the prize.
Scenario 8
I choose Door C. You choose Door B.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I lose the prize.
You change your choise, you win the prize.
Scenario 9
I choose Door C. You choose Door C.
Whoever manages the doors opens one and shows it has nothing.
I keep my choise, I lose the prize.
You change your choise, you win the prize. |
Uhm, it seems you would win more times than I do. lol
Still doesn't make too much sense. |
It is an old puzzle that one. I think it was originally some 1950s or 1960s american quiz show and there were goats behind the doors.
There were quite a few mathimatical studies done on it both theoretical and practical (by opening 10,000s of doors) and the out come of all of these were that you had a higher chance of winning by switching doors after the first empty one was opened. |
You've been ambushed, and thrown in a dark cold room with TWO doors to stay and rot there.
You are given however a chance: You can choose one of the doors to go through. However, one of the doors leads to Freedom, while the other door leads to a Dragon's mouth/stomach.
To help you out in your choice, each doors has one guard that will lock the door behind you as soon as you've passed through. Before making your choice and irreversibly passing through one of the doors, you can ask ONLY one question to ONLY one of the guards. The guard will answer to you ONLY either "Yes" or "No".
How can you ALWAYS go to freedom?
Just one more detail: The guards know each other, and they know where the doors lead. However, one of the guards always says the TRUTH, while the other guard always LIES. You don't know which one says the truth/lies, and you don't know which guard is behind which door. See you on the other side! Good luck!... |
#76 By far the easiest question in this topic, you do not even need to ask any questions, the doors will not have the same odor... o.o
There are thousands of ways around this riddle without asking a question...
Also note that you just stole a riddle... and edited it a little bit...
(Yugioh also stole this riddle XD) |
For my question:
LOL DiN, my bad. its high school to be exact, but I totally forgot the thread title :P
abdullah, it was meant as 0.2% per minute for 3 hours (180 mins).
But its alright, no need to solve such an outplaced question, my bad. Heh.
arc |
#75
That's right.. it is an old problem.
You can read about it... just search for "Monty Hall problem". |
An easy one:
If a redhouse is made from redbricks,a yellowhouse is made from yellowbricks what is a greenhouse made from? |
