How can u measure a defective ball weighing less than the other 8 balls using a balance twice?

Question

You have 8 balls One of them is defective and weighs less than the others Use a balance to measure balls against each other. Doing this twice how do you find the defective one??

Answer 1

Measure 6 balls three on each side

If that balances, then the light ball is one of the other two.  measure them against each other and you have your answer

If the 6 ball (3-3) does not balance, take two of the three from the lighter group and measure them.  If they balance, the third is the light ball.  If they don't balance you have the lighter ball.

Answer 2

-Put 2 balls apart

-Measure 3balls vs the other 3

And from here we have 2 possibilities:

1) If the weight is the same, you take the two balls that put apart  and measure one against the other and you will find which one weights less.

2) If one group of 3 balls weight less, then you put one of them apart and  then measure one against the other. Then we have 2 possibilities:

a) The balls weight the same, it means the ball we put apart is the defective one.

b) One weights less than the other, so we have the defective ball.