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

Detached SG

put 6 balls a side, the heavier one is what we want.

divide the heavier group into 2 groups of 3.

den weigh again, and there'll be a heavier side again.

den from that side, pick 2 random balls and weigh them against each other.

if 2 same weight, the one left behind heavier lo.

if 2 no same weight, den obviously the heavier one is there.

hurhur

Wrong. Firstly, you don't know if the odd ball is lighter or heavier, so you wouldn't know which group of 6 does the odd ball belongs to.

And if we were to use your method and weigh 2 random balls out of the final 3 - we still wouldn't know which is the odd ball... Simply because.. WE DON'T KNOW IF THE ODD BALL IS LIGHTER OR HEAVIER!

Edit: But still good attempt there, I guessed the exact same thing as you when I first chanced upon this question

ChoCoChips SG

yes, if you think about it.

reveal the answer later.. but i think Choco knows the answer already

i where got so smart

hurhur

ChoCoChips SG

Wrong. Firstly, you don't know if the odd ball is lighter or heavier, so you wouldn't know which group of 6 does the odd ball belongs to.

And if we were to use your method and weigh 2 random balls out of the final 3 - we still wouldn't know which is the odd ball... Simply because.. WE DON'T KNOW IF THE ODD BALL IS LIGHTER OR HEAVIER!

oh ya hor.

weighs a lil different!

aiyo!

wait ar.

lemme think abt it and fine tune my ans

skythewood SG

divide the 27 balls into 3 groups, A, B, C

Step 1: compare group A & group B

results/conclusion: if A is heavier. the heavier ballis in set A.

if B is heavier. the heavier ballis in group B.

If A and B same weight, ball is in group C.

divide the group with heavier ball into 3 sets, A, B, C

Step 2: compare set A & set B

results/conclusion: if A is heavier. the heavier ballis in

group A.

if B is heavier. the heavier ballis in set B.

If A and B same weight, ball is in set C.

divide the set with heavier ball into 3 balls, A, B, C

Step 3: compare ball A & ball B

results/conclusion: if A is heavier. the heavier ballis in ball A.

if B is heavier. the heavier ballis in ball B.

If A and B same weight, ball is in ball C.

ChoCoChips SG

im thinking abt grps of 4 one.

1st group against 2nd group, den 3rd group. from there can see which one heavier/lighter.

den from that group take 2 against 2.

but i'll need more than 3 tries.

tsk tsk tsk

Detached SG

divide the 27 balls into 3 groups, A, B, C

Step 1: compare group A & group B

results/conclusion: if A is heavier. the heavier ballis in set A.

if B is heavier. the heavier ballis in group B.

If A and B same weight, ball is in group C.

divide the group with heavier ball into 3 sets, A, B, C

Step 2: compare set A & set B

results/conclusion: if A is heavier. the heavier ballis in

group A.

if B is heavier. the heavier ballis in set B.

If A and B same weight, ball is in set C.

divide the set with heavier ball into 3 balls, A, B, C

Step 3: compare ball A & ball B

results/conclusion: if A is heavier. the heavier ballis in ball A.

if B is heavier. the heavier ballis in ball B.

If A and B same weight, ball is in ball C.

I don't see how this question is 'up-ed'

When you stated the odd ball is heavier.. it already made things easier

Anyway, back to my original question. Any takers? I'll be back in an hour to reveal the answer!

ChoCoChips SG

divide the 27 balls into 3 groups, A, B, C

Step 1: compare group A & group B

results/conclusion: if A is heavier. the heavier ballis in set A.

if B is heavier. the heavier ballis in group B.

If A and B same weight, ball is in group C.

divide the group with heavier ball into 3 sets, A, B, C

Step 2: compare set A & set B

results/conclusion: if A is heavier. the heavier ballis in

group A.

if B is heavier. the heavier ballis in set B.

If A and B same weight, ball is in set C.

divide the set with heavier ball into 3 balls, A, B, C

Step 3: compare ball A & ball B

results/conclusion: if A is heavier. the heavier ballis in ball A.

if B is heavier. the heavier ballis in ball B.

If A and B same weight, ball is in ball C.

eh but 1 gram leh.

how u noe the scale is accurate?

hw u noe u can see a difference?

haha

would've solved it nt for the 1 gram.

lol

Chris1988 SG

the question is, you don't know if the odd ball is lighter or heavier

Daisuke-kun SG

so easy lar.

u do 3 steps, den u ask another person to do another 3 steps.

keep the chain going until u get the answer.

Detached SG

There is a weighing balance and 12 balls. The 12 balls all look the same from the outside, but 1 weighs a little different from the other 11.

Using the weighing balance not more than 3 times, find out which is the odd ball and whether it is lighter or heavier :P

-UNSOLVED-

Note: You do not know if the odd ball is lighter or heavier. TS will be back in an hour to reveal the answer!

freedom4ever SG

hmm.. i kind of forgot the answer already. but still remember that the first steps is divide the 12 balls into 3 groups of 4 and then take any 2 groups to have their first reading taken. the rest forgot liao.

freedom4ever SG

There is a weighing balance and 12 balls. The 12 balls all look the same from the outside, but 1 weighs a little different from the other 11.

Using the weighing balance not more than 3 times, find out which is the odd ball and whether it is lighter or heavier :P

-UNSOLVED-

Note: You do not know if the odd ball is lighter or heavier. TS will be back in an hour to reveal the answer!

not so fast leh. i still trying to recall.

skythewood SG

For TS question,

divide the 12 balls into 3 groups, A, B, C

Step 1: compare group A & group B

results/conclusion: if A and B is not same weight. conclusion (I)

If A and B same weight, ball is in group C. conclusion(II)

From conclusion (II) the diff weight ball is in C,

Step 2: compare 3 balls from A & 3 balls from C

results/conclusion: if A and C is same, the odd ball is unweighed ball in C.

if A and C is different, the odd ball is in weighed ball in C

take note whether the ball is heavier or lighter

Step 3: compare 2 of the 3 ball in C

results/conclusion: if unequal, one of them is the ball

if equal, the unmeasured is the ball

parn SG

By weighing balance, I meant a non electronic scale (imagine the see-saw)

And also, by removing any ball from the balance, it automatically counted as another usage on the balance.

You very ma-fan one.....

Put six balls on each side, remove 3 balls from each side first, then followed by 2 balls if they are still balance, then you know which ball is unbalance.

The key is to keep weighing the unbalance balls, be it 3 on each side or 2 on each side. Remember to keep replacing the balance balls with the unbalance balls and stuff them into Detached's mouth and then continue until you get 1 ball on each side.

ChoCoChips SG

You very ma-fan one.....

Put six balls on each side, remove 3 balls from each side first, then followed by 2 balls if they are still balance, then you know which ball is unbalance.

the very impt thing is 3 tries nia leh

Master -_- SG

i know the answer...just have to number the balls from 1 to 12...very tiring if post the whole scenarios..

Chris1988 SG

i know the answer riao i think. but quite long winded

skythewood SG

From conclusion (I)

mark the heavier side as H1-H4, light side as L1-4, group C ball as S

Step 2: compare H1, H2, L1 against H3, L2, S

results/conclusion = if all the same, the problem ball is H4 is heavy, L3 or L4 is light (A)

= If H1. H2, L1 is heavier, means H1, H2 heavy or L2 is light (B)

= if H3, L2, S is heavier, means H3 is heavy or L1 is light (C)

skythewood SG

From conclusion (A)

Step 3: compare L3 and L4

results/conclusion = if same, H4 is heavy

= if not same, lighter one is lighter

From conclusion (B)

Step3: compare H1 and H2

results/conclusion = if same, L2 is light

-heavier one is heavy

From conclusion (C)

Step 3: compare H3 with S

results/conclusion = if same, L1 is light

= if not, H3 is heavy

skythewood SG

not going to check working le, but you guys get the idea.

How difficult is it to weight the balls like 5, 6 times? KNN......

« Previous Page Next Page »