Maths Teaser

[Bold Seagull]

50% isnt it - you are either right or wrong.

If 50% is the right answer, what are your chances of picking 50%!?

 

[StonehamPark]

If anyone can explain the answer to this, I'd be grateful. It's been bugging me for ages now...

This puzzles intention is to confuse the reader with it's fairly clever presentation of answers.
The only and correct answer is 25% chance that you will answer the question correctly. However you are not choosing an actual answers e.g: A) x B) x C) x D) x
These options don't make an ounce of difference to the asked question.

This is of course just my calculated guess!

 

[StonehamPark]

This is an old one....

You're on a game show and the host shows you three doors (A,B and C), behind two of the doors is a goat, behind the third is a car. He asks you to choose a door and you choose (for example) door A.

The host opens door B and shows you a goat (he will always show you a goat behind one of the other doors).

He give's you the option of sticking with Door A or changing to Door C.

Do you stick or change and what are the probabilities that your dealing with?

Surely the only possible answer could be 50%. Whether you stick with Door A or switch to Door C you still have a 50/50 chance of opening the correct door after Door B has been opened.

 

[pauli cee]

Where's the question? It's a play on words isn't it, not numbers.

exactly this.
ever seen that film "the exam" ?

 

[leigull]

Surely the only possible answer could be 50%. Whether you stick with Door A or switch to Door C you still have a 50/50 chance of opening the correct door after Door B has been opened.

Nope you have 2/3's the chance of being right when you swap as opposed to 1/3 if you stick

 

[SeagullSongs]

Surely the only possible answer could be 50%. Whether you stick with Door A or switch to Door C you still have a 50/50 chance of opening the correct door after Door B has been opened.

2/3.
If you pick door A:

If the car is behind door A, he opens B or C, both of which contain goats. If you switch (from A to B or C) then you get a goat.
If the car is behind door B, he will open C with a goat behind it. If you switch (from A to B) you win the car.
If the car is behind door C, he will open B with a goat behind it. If you switch (from A to C) you win the car.

If you pick door B:

If the car is behind door A, he will open door C with a goat behind it. If you switch (from B to A) you win the car.
If the car is behind door B, he will open door A or C, both with goats behind them. If you switch (from B to A or C) you get a goat.
If the car is behind door C, he will open door A with a goat behind it. If you switch (from B to C) you win the car.

If you pick door C:

If the car is behind door A, he will open door B. If you switch (from C to A) you win the car.
If the car is behind door B, he will open door A. If you switch (from C to B) you win the car.
If the car is behind door C, he will open door A or B, both with goats. If you switch (from C to A or B) you get a goat.

9 options, 6 win the car.
If you always switch, there is a 2/3 chance you win the car.

 

[South Stand Bonfire]

I would also go with this.

Or more likely 33.33% if equal chance of answer being 25%, 50% or 60%.

 

[Brightonfan1983]

Surely the only possible answer could be 50%. Whether you stick with Door A or switch to Door C you still have a 50/50 chance of opening the correct door after Door B has been opened.

I know, but check this out - Monty Hall Problem -- from Wolfram MathWorld

 

[bn1&bn3 Albion]

1/3 or 33.33%

 

[Dunk]

With the Monty Hall problem it is best to swap. IF you swap, the only way you can lose is if you picked the car first time- which is a one in three chance. That means a two thirds chance of winning.

I like the original problem a lot. I'm fairly sure there is no real solution but it makes you think.

 

[DanielT]

Is there any such thing as random?

 

[Bisto]

How about this one?

Me and my two flat mates were after a decent big new telly for the flat, and a mate of ours said he had seen a peach of an LED full HD 32 inch for exactly £300, and he could pick it up for us on his way home from work next day.

So in the pub that night we each gave him £100, so he could go out and buy the £300 TV.

He went to the shop, and to his delight the price had been reduced even further, to just £250. He obviously thought he would keep quiet about this further discount and pocket the £50 himself.

But his conscience got the better of him, so when he delivered the telly to us he said he got it for £250. And as £50wasn't easily divisible by 3 he said "how about I give you £10 back each, and I keep the other £20 for my trouble, time and petrol money?". And we all thought 'fair enough, he's done us a proper good turn here'.

So at the end of the day, we had each given him £100, but he had given each of us a tenner back. So each of us had parted with £90. Three times £90 is £270, add on the £20 he kept for himself, makes £290.

Hang on a minute, so where's the other tenner gone?

Your flat mate is too devious MOVE OUT NOW!!!

 

[StonehamPark]

What happens when an unstoppable force meets an unmovable object?

 

[Arthritic Toe]

This is an old one....

You're on a game show and the host shows you three doors (A,B and C), behind two of the doors is a goat, behind the third is a car. He asks you to choose a door and you choose (for example) door A.

The host opens door B and shows you a goat (he will always show you a goat behind one of the other doors).

He give's you the option of sticking with Door A or changing to Door C.

Do you stick or change and what are the probabilities that your dealing with?

The answer is: it depends on whether you want to win a car or a goat.

 

[Pevenseagull]

b