ChiefKiasu:

limlim:

if he stick to his original choice, the chance of picking his child's name is 1/3.


If he switch, the chance of picking his child's name is 2/3.

LOL... limlim is the genius that has no common sense but has a high IQ. Congratulations!
:congrats:

wonderm:

Ah Seng took $2 from the $297 paid by the parents, the distributor got $275 for the 3 books. $297-$2=$295. No missing $1.


Hey, this one is meant for the parents or the kids?

ChiefKiasu:

Here's another one.


3 parents pooled together a total of $300 to buy and share an encyclopedia set from Ah Seng who is organising an Mass Order from a distributor. The distributor decided to give a further discount of $5 for each encyclopedia set sold. Ah Seng decides to keep $2 and return the rest of the discount to the parents, so each of them gets $1 back.
So,
Each parent paid $100-$1= $99
3 parents paid = $199x3 = $297
Ah Seng took = $2
Total = $299

So what happened to that missing $1 ??

ChiefKiasu:

Here's another one.


3 parents pooled together a total of $300 to buy and share an encyclopedia set from Ah Seng who is organising an Mass Order from a distributor. The distributor decided to give a further discount of $5 for each encyclopedia set sold. Ah Seng decides to keep $2 and return the rest of the discount to the parents, so each of them gets $1 back.
So,
Each parent paid $100-$1= $99
3 parents paid = $199x3 = $297
Ah Seng took = $2
Total = $299

So what happened to that missing $1 ??

ChiefKiasu:

Speaking of which, can parents solve this completely hypothetical problem?


3 parents want to get into a school with only 2 remaining vacancies. The names of their children are written down and placed in a ballot box.

One of the parents insisted on being the first to draw. The Principal decided to make it more interesting. The parent will get to draw, but if the ballot he opens is his son's name, then his son will be eliminated and the other 2 parents will get the places in the school.

However, before the parent opens the ballot, the Principal will remove one of the remaining 2 ballots in the box that does NOT contain his son's name. The parent will then get to decide to open either the original ballot he removed, or choose to open the last remaining ballot in the box instead.

What should the parent do?
A) Choose to open his original ballot
B) Choose to open the remaining ballot in the box?
C) It makes no difference whether we choose A or B.

:evil:

Sun_2010:

Soli soli , he should choose option B if he wants to eliminate his son .


I didnt not that part of the twist.

You turned out to a twisted penguin :razz:
( that is a compliment , dun :torchme: )

limlim:

Sun_2010:

[quote=\"Sun_2010\"]
Chief you testing our IQ ah?

Option B of course , if we trust probability.

Soli soli , he should choose option B if he wants to eliminate his son .

I didnt not that part of the twist.

You turned out to a twisted penguin :razz:
( that is a compliment , dun :torchme: )

Sun_2010:

Sun_2010:

Chief you testing our IQ ah?

Option B of course , if we trust probability.

Soli soli , he should choose option B if he wants to eliminate his son .

I didnt not that part of the twist.

You turned out to a twisted penguin :razz:
( that is a compliment , dun :torchme: )

Sun_2010:

ChiefKiasu:

Speaking of which, can parents solve this completely hypothetical problem?


3 parents want to get into a school with only 2 remaining vacancies. The names of their children are written down and placed in a ballot box.

One of the parents insisted on being the first to draw. The Principal decided to make it more interesting. The parent will get to draw, but if the ballot he opens is his son's name, then his son will be eliminated and the other 2 parents will get the places in the school.

However, before the parent opens the ballot, the Principal will remove one of the remaining 2 ballots in the box that does NOT contain his son's name. The parent will then get to decide to open either the original ballot he removed, or choose to open the last remaining ballot in the box instead.

What should the parent do?
A) Choose to open his original ballot
B) Choose to open the remaining ballot in the box?

:evil:

Chief you testing our IQ ah?

Option B of course , if we trust probability.

ChiefKiasu:

SAHM_TAN:

Very stress testing common sense becos I value common sense over IQ LOL.


Hmmmmm I choose A bah

Keke... why did you choose A?

ChiefKiasu:

wonderm:

In this case, since the Principal has removed one other boy's name, the chance that the one left in the box is my son's name is 50%, 1 out of 2 (1 in the box, 1 in my hand).


When I first pick one slip out of 3, the chance of picking my son's name was 1/3. That's why I will choose A.

Why does the Principal think that one who knows about probability does not have common sense?

Don't worry, your reasoning shows you have common sense. Just that your probability calculations is a little flawed The probability that the ballot remaining is the box is the father's son is quite a bit higher than 1/2. It is 2/3 like limlim rationalised.

This is the inverse Monty Hall problem. Read up the article on http://en.wikipedia.org/wiki/Monty_Hall_problem to understand why.

wonderm:

In this case, since the Principal has removed one other boy's name, the chance that the one left in the box is my son's name is 50%, 1 out of 2 (1 in the box, 1 in my hand).


When I first pick one slip out of 3, the chance of picking my son's name was 1/3. That's why I will choose A.

Why does the Principal think that one who knows about probability does not have common sense?

ChiefKiasu:

wonderm:

I will choose A because 1/3 the chance it is my child's name, if I chose B, the chance is 1/2.


Correct or not?

Not sure if I hope to get the answer right, that means no common sense leh :nailbite:

Why is the chance of chosing B 1/2?

limlim:

if he stick to his original choice, the chance of picking his child's name is 1/3.


If he switch, the chance of picking his child's name is 2/3.

Iluvmygals:

Option


1. Principal remove a paper that is not his son's name.
2. So left with 2 paper - one with his son name and one with another child's name.
3. The fact is no matter how he choose between these 2 papers...his son won't get in. If his paper is his sons name...his son won't get in...if the paper is the other child's name, the other child will get it..his son won't get it...

So it doesn't matter what he choose.....

wonderm:

I will choose A because 1/3 the chance it is my child's name, if I chose B, the chance is 1/2.


Correct or not?

Not sure if I hope to get the answer right, that means no common sense leh :nailbite:

Pen88n:

When the principal takes out one remaining ballot, he can either:

1) Put it back because it is the son's name
2) Remove it because it is not the son's name

If action is (1), definitely it is better that parent choose (A) open his original ballot. If action is (2), it points to (C) makes no difference whether choose A or B as the parent would not know for certain the ballot at hand or in the box contains his son's name. So, all options evaluated, the parent should choose (A).