Brain Teasers

1. Coloured weights: This is a variation on an old problem. You have six weights. One pair is red, one pair is blue and one pair is white. In each colour one weight is a little ehavier than the other but they look exactly alike. All the heavier weights (in each colour) weigh the same and so also the lighter weights.
Using only two separate weighings on a balance, how can you identify which is the heavier weight of each pair?
2. Arrange 10 Re. 1 coins (or any identical coins) in a triangle or bowling pin format as shown. In your mind, join the centres of each coin to each other. You can see several shapes, including several equilateral triangles. What is the smallest number of coins you must remove so that you will not be able to draw an equilateral triangle of any size with the coins as centres?

From Mathematical Circus, by Martin Gardner