Question

There are nine identical looking
pearl. Eight are real and one is
fake. Using a balance scale that
consists of two pans, you must
find the lake pearl
Information: The real pearls
weigh the same and the fake
weighs less.
Condition: The scale can be used maximum twice.
Explain your answer. ​

Answer 1

Step-by-step explanation:

1st Use:

Take 6 pearls and divide it into two groups of 3 pearls each and place it on each balance.

Two cases arise:

• 1st case: Scale is balanced. i.e the fake pearl is part of the three remaining pearls
• 2nd case: Scale is unbalanced. Then the fake pearl is part of the group which weighs less. Pick that one

2nd Use:

Once you pick the group containing the fake pearl, select 2 pearls from the remaining three and place each one on the balance.

Again 2 cases arise:

• 1st case: If scale is balanced, then the fake pearl is the last one remaining.(one not selected)
• 2nd case: If scale is unbalanced, the fake pearl is the one which weighs lesser on the balance.