Post a New Question


posted by .

A man selling fruit has only three weights. But with them he can weigh any whole number of kilograms (from 1 kg to 13 kg) inclusive on his balance.

What weights does he have?


math - Kalyan, Friday, September 5, 2008 at 4:38am
The man had 1kg, 3kg and 9 kg weights.

How do you set it up to get this answer? Any ideas?

  • Math -

    You can prove to yourself that 1,3 and 9 work. With them, you can form counterbalances of
    1, 2 (3-1), 3, 4 (3+1), 5 (9-1-3),6 (9-3), 7 (9+1-3), 8 (9-1), 10 (9+1), 11 (9+3-1), 12 (9+3) and 13 (9+3+1)

    A minus sign means putting the weight on the same side of the balance as the weighed object.

    Proving that other combinations will not work is harder, but is not necessary.

Answer This Question

First Name:
School Subject:

Related Questions

More Related Questions

Post a New Question