The Official IQ Questions Thread

last SG · 2008-09-03T22:19:02+00:00

wah..smart.the q is tough, but the answer is eben tougher!hahaha

Three3am SG

skytheword,

would appreciate if you can explain the rat solution in greater details.. thanks.. i dont understand.. :(

darkensun SG

skythewood... if the host have to open one door with goat as a rule...the percentage of you getting the car will become 50%....
However(which I think you mean this way), if after you choose a door did the host decide to give you the chance...yes I will change...it thes monty thing....

ChoCoChips SG

eH!

why got monty hall?

hahaha

change la.

should change.

ChoCoChips SG

i post one easy one

every couple in country A wans to a boy.

they will keep making kids until they get a boy la, i.e if they get a girl den they continue until they finally get a boy.

now, wad's the proportion of boys to girls in country A.

skythewood SG

skytheword,

would appreciate if you can explain the rat solution in greater details.. thanks.. i dont understand.. :(

ok, let's say got 1 rat, 2 bottles, A, B

rat drink A. if rat dies, A is poison. rat live, B is poison.

two rats, 1 ,2, four bottles, A, B, C, D.

| A | B | C | D
rat 1 | drink |drink | |
rat 2 | drink | |drink |

if rat 1 dies, means B is poison.
If rat 2 dies, means C is poison.
If both die, means A is poison
If both live, means D is poison

three rats, 1, 2, 3, eight bottles, A, B, C, D, E, F, G, H

   | A   |   B   |   C   |   D   | E   |   F   | G   |   H
rat 1 | drink |drink | |   | drink |drink | |
rat 2 | drink | |drink |   | drink | |drink |
rat 3 | drink | | | drink | |drink |drink |

if rat 1 dies, means B is poison.
If rat 2 dies, means C is poison.
If rat 3 dies, means D is poison.
If 1, 2 dies, means E is poison
If 1, 3 dies, means F is poison
If 2, 3 dies, means G is poison
If all lives, means H is poison
If all dies, means A is poison

conclusion

so 1 rat can test 2 bottles,
so 2 rat can test 4 bottles,
so 3 rat can test 8 bottles,
so 4 rat can test 16 bottles,
so 5 rat can test 32 bottles,
so 6 rat can test 64 bottles,
so 7 rat can test 128 bottles,

skythewood SG

3 doors, two goat, 1 car.

if you choose randomly at the beginning, your chances of getting a goat is 1/3.
there is a 2/3 chance you won't get a car.

now, let's say the host remove one of the goat.

there is a 2/3 chance that the door left is a car.
there is still a 1/3 chance you have chosen a goat.

so it is better to switch.

skythewood SG

i post one easy one

every couple in country A wans to a boy.

they will keep making kids until they get a boy la, i.e if they get a girl den they continue until they finally get a boy.

now, wad's the proportion of boys to girls in country A.

assume each birth is independent. assume there is 32 pair of couples

1st birth

chances of getting a boy and stop is 50% ==> 16
chances of getting a girl and try again is 50% ===>16

2nd birth

chances of getting a boy and stop is 50% ==> 8
chances of getting a girl and try again is 50% ==> 8

3rd birth

chances of getting a boy and stop is 50% ==> 4
chances of getting a girl and try again is 50% ==> 4

4th birth

chances of getting a boy and stop is 50% ==> 2
chances of getting a girl and try again is 50% ==> 2

5th birth

chances of getting a boy and stop is 50% ==> 1
chances of getting a girl and try again is 50% ==> 1

as shown, number of boys and girls are the same.

purpledragon84 SG

3 doors, two goat, 1 car.

if you choose randomly at the beginning, your chances of getting a goat is 1/3.
there is a 2/3 chance you won't get a car.

now, let's say the host remove one of the goat.

there is a 2/3 chance that the door left is a car.
there is still a 1/3 chance you have chosen a goat.

so it is better to switch.

i dun buy that.. haha.. i choose to think it's 50-50.. stats and prob is full of crap sometimes..

skythewood SG

i dun buy that.. haha.. i choose to think it's 50-50.. stats and prob is full of crap sometimes..

if you don't switch, the chance of you winning will always be 1/3.

even if you think stats is crap, you will have to agree with me on that, right?

ChoCoChips SG

assume each birth is independent. assume there is 32 pair of couples

1st birth

chances of getting a boy and stop is 50% ==> 16
chances of getting a girl and try again is 50% ===>16

2nd birth

chances of getting a boy and stop is 50% ==> 8
chances of getting a girl and try again is 50% ==> 8

3rd birth

chances of getting a boy and stop is 50% ==> 4
chances of getting a girl and try again is 50% ==> 4

4th birth

chances of getting a boy and stop is 50% ==> 2
chances of getting a girl and try again is 50% ==> 2

5th birth

chances of getting a boy and stop is 50% ==> 1
chances of getting a girl and try again is 50% ==> 1

as shown, number of boys and girls are the same.

correct!

fwah u ish smart boy!

skythewood SG

haha, thank you..

think detached and friends is busy, that's why they never answer your Q

purpledragon84 SG

an eye opener..

http://math.ucr.edu/~jdp/Monty_Hall/Monty_Hall.html

haha..

elementalangel SG

ai yo let me try

got 12 balls

break into 2 groups

6 balls each for both group A and group B. Weigh both groups

this take any random ball and weigh.

there u weighed 3 times le.

the random ball multiply by 6, if the weight exceeds the weight of both group A and B then its the extra ball, its the same if its weight is less than both groups.

however if its weight when multiplyed by 6 is exactly the same as one of the groups, it is the weight of one of the 11 balls.
Then you can multiply it by 5 and use the latter group multiplied by 6 to minus the answer, thus u get the answer of the extra ball.

TADA!!

skythewood SG

an eye opener..

http://math.ucr.edu/~jdp/Monty_Hall/Monty_Hall.html

haha..

yup... switching is basically betting that you will not pick the car.

skythewood SG

there are 2 types of people on an island, heroes and villians.

you met a local, A, but did not hear what he says.

B, another local says "A just said that he is a villian"

C, another local says "he is lying! A is a hero!"

the question is, whether C is a villian or a hero.

skythewood SG

no one want to answer... sad....

ChoCoChips SG

wad q?

skythewood SG

there are 2 types of people on an island, heroes and villians.

you met a local, A, but did not hear what he says.

B, another local says "A just said that he is a villian"

C, another local says "he is lying! A is a hero!"

the question is, whether C is a villian or a hero.

this one

ChoCoChips SG

hero n villian got wad characteristics?

skythewood SG

heroes are righteous and tells the truth...

villians are bastards and tell lies...

sorry, forgot to include characteristics.... no wonder no one want to answer...

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