Math Question?

Question

You have 8 steel balls, all look and weigh exactly the same, except for 1, it is a little bit different in weight.
Now you have an old type scale were the heavy side will go down and the lighter side up.
You are allowed to use the scale only twice, and must than be sure which of the 8 is the odd one. How do you do it?

Answer 1

It can't be done, unless you know if the odd one is too light or too heavy. If you know it's too heavy, put three on each pan; if it balances you can just test the other two and if not take two of the balls on the heavy side and test them. If they balance, it's the third one, if not, it's the heavier one. Do it similarly if you know the oddball is too light.

Answer 2

Divide them into two groups. One with 6 and the other with 2.

Weigh the group of 6 first putting three on each side. If they're equal then you know the lighter ball is in the group of two, so weight the group of 2 putting 1 on each side. Thus you will know which is odd using the scale only twice.

Now, when you split the group of 6 into two groups of 3 and the scale is not even take the three balls from the lighter side and weigh two of the balls. If the balls are equal, then you know the odd ball is the one that was not weighed. If they are not equal then you will still know which one was the odd ball.

Answer 3

I want to ask that how many balls can u put in one side of the scale at one time?



If u can put 4 balls in each side of the scale, the lighter side shows that there is a lighter ball in there.



Take 4 balls from the heavier side down.

Put 2 balls from the lighter side to the other side. So u now have 2 balls on each side of the scale. The lighter side will have the odd one.



Take 2 balls from the heavier side down.

Put 1 ball from the lighter side to the other side. So u now have 1 ball on each side of the scale. The lighter side has the odd ball.



I dont know how u can determine the odd ball just by using the scale twice.

Answer 4

Put 4 balls on one side and the other 4 on the other side. The lighter of the 2 sides obviously has the lighter ball. Your now down to 4 balls, 1 of which is the odd ball. split those 4 balls up into 2 groups of 2 and weigh them. Your now down to 2 balls, one of which is the odd ball. Take your 50-50 chance and guess. Do you know the answer?

Answer 5

Put 2 balls aside, and put the remaining 6 on the scale 3 on one side 3 on the other, 1 of 2 things will happen, one side will go up,other down or they will stay equal. If they stay equal remove all 6 and measure the other two, one will show the different weight. If it is uneven the first time, assuming the ball is heavier it is within the 3 that went down. If it is lighter obviously you want to 3 that go up. Take 2 of the 3 left and measure, if they are uneven, the onle of them on the scale is it, if they are even its the 3rd one left.

Answer 6

first split the balls into two groups of 3, and a group of 2. first put one group of 3 into each hand of the scale. Two scenarios will occur:



1. the scale will balance. If this happens then the defective ball must b in the group of two. This means that all you have to do is put one of the two balls in each hand and see the one that weighs diffrent.



2.the second scenario is if one side is unbalanced, the side that is diffrent contains the defective ball. Therefore take out the three balls and pick any random two. Put one of these two in each hand of the scale. The side that tips has the defective ball. If they balance, the one ball left is the defective one.



Have fun!!!

Answer 7

For using the scale only twice, it is required to put 3 balls on each side. If these 6 are perfectly equal, then the hollow ball is not in them. So, then we put the remaining 2 balls, each on each side. Then the side, which goes up contains the hollow one.

However, if when we place 3 balls on each side and a side goes up, then we discard the balls on the side which goes down. Then from the 3 balls which go up, we put one on each side. If both are equal, then the third one is hollow. But if, one goes up and another up, then the ball which goes up is the hollow one.

Answer 8

Considering your question is exactly what you want, then I would say these people with "solutions" are incorrect. The one "odd" ball has a different weight. Unfortunately, you don't know if it is heavier or lighter, so you can't determine which side has the "odd" ball. Just to let you know. I'll get back to you when I figure it out.

Answer 9

First divide the eight balls into 3 3 and 2...keep the two three balls in each pane of the scale..if it is balanced then the defective ball is in the 2 balls group..if any one side goes down then the defective one is in that side..if you find defective in the two balls group then nothing to do just put it in both hands and you can find the defective..if u find the defective in the three ball group then take that and put each one in each hand..you will have left with one ball in hand.if both the hands are balanced then the defective one is in your hand if not the defective one will be in the side which is down....

Answer 10

the different weight ball is lighter o heavier?

knowing that try 3 on each side, if is even try the other 2 balls, if not put 1 ball on each side of the 3 that demonstrate that have our required ball. making it we gonna notice which is the different weight ball.

Answer 11

Once 2 ( one on either side) are even. weigh the rest against one of the original balls until you get a miss match

Answer 12

College Boy got in first with the correct answer.

Answer 13

place 4 balls on ea. side, then subtract half until you can see difference.