You're not weighing two sets of four weights on your first use of the scale, are you?
US Version
If you do that, you'll only have one more chance left to determine which of four weights is the light one.
But you probably already know that, right?
UK Version
If you do that, you'll only have one more chance left to determine which of the four weights is the light one.
But you probably already know that, right?
Maybe thinking about another example will help you out here. Imagine you have three weights, one of which is lighter than the rest.
US Version
To find the light weight, all you gotta do is weigh any two of the three. If one of the weights on the scale is lighter, there's your answer. If the two weights on the scale are the same, the remaining weight is the light one.
UK Version
To find the light weight, all you have to do is weigh any two of the three. If one of the weights on the scale is lighter, there's your answer. If the two weights on the scale are equal, the remaining weight is the light one.
US Version
Think about the last hint. You can figure out the light weight in a group of three with one use of the scale.
If you can narrow the number of weights in question to three in one use of the scale, you've got your answer.
UK Version
Think about the previous hint. You can work out the light weight in a group of three with one use of the scale.
If you can narrow the number of weights in question to three in one use of the scale, you've got your answer.
Solution
Incorrect
Too bad!
The light weight changes each time you try the problem. Think about what you need to do and try again.
Correct
That's right!
To solve this puzzle with no guesswork, you must load three weights on each side of the scale for your first measurement. If you manage to get that far, the rest is easy.
