How many iteration u take?

Question

I have 8 balls , 7 are of equal weights and one is heavier that the 7, Now I give u all the 8 balls,
How many iteration u take to tell which one is heavier ....
u are allowed to use weighing machine...

Answer 1

You can do it in two steps:

1st step:
Put 3 balls on either side of the scale. If the scale levels out you know the heavy ball is one of the remaining 2 balls.

2nd step (a):
If the scale was level in the first step, place the two balls NOT weighed in the first step on the scale. The heavier of the 2 will be the heavy ball.

(b)
If the scale was NOT LEVEL in step 1, take two of the balls on the heavy side of the scale and place them on either side of the scale. If the have the same weight the third ball will be the heavy on. Of one of them is heavier than the other you have isolated the heavy ball.

Answer 2

Balance Scale:
3 weighs:
Divide the balls into 2 groups of 4, weigh them against each other.
Divide the heavier group into 2 groups of 2, weight them against each other.
Weigh the two balls from the heavier group against each other, the heavier of the two is the right one.

Normal Scale:
4 weighs:
Divide into two groups of 4 and weigh each. You should then know the weight of the heavier ball.
Divide the heavier group into two groups of 2 and weigh one of them. You should know whether or not this is the group with the heavy ball, since we now know the weight of the heavy ball.
Weigh one of the balls in the heavier group. You should now know which of the 2 balls is the heavy ball.

Answer 3

2 iterations using a balance,
Weigh 3 balls against 3 balls.
If one group is heavier, weigh any 2 against each other. If one is heavier it is the heavy ball. If they are equal, the remaining ball is the heavy ball.

If the two groups are equal, balance the last two against each other to find the heavy ball.

Answer 4

Minimum 2 iterations if there is a weight difference in the first two balls i pick. If the second ball i pick is heavier then the first one, then the second one is THE heavier ball. If the second ball i pick is lighter than the first ball then the first one is THE heavier ball.

Maximum - 7 iterations if the heaviest ball is picked last

Answer 5

Minimum to guarantee finding the heavier ball is three.
First split the group four and four. Which ever group is heavier has the heavy ball. Take that group and split it two and two. Which ever is heavier has the heavy ball. Then weigh the two balls seperately and find the heavy ball.

Answer 6

2
divide into 3 groups of 3,3, and 2.
compare both group of 3.
anywhich heavier have the heavy ball. if both are same, the one in group of 2 have the heavy ball.
compare any 2 of them. the heavier is the heavy ball. if the compared 2 have same weight, the one not compared is the heavy ball.

Answer 7

max 4 weights

Answer 8

Well I feel it can be checked in max. six(6) attempts. Can happen in the very fisrt attempt or max. in 6 attempts.

Answer 9

3

Doug