Brainteasers

25th May 2001 at 01:00
Puzzles to test mathematical skills.

AGE 5-7: LINE UP THE CLOWNS

Five clowns stand in a line

The BLUE nose is three perfect places to the right of the RED nose.

The GREENnose is left of the BLUE nose but right of the pink nose.

The YELLOW nose is 3 places to the left of the green nose.

Where in the line is each clown standing?

AGE 8-10: Make triangles

Imagine you have a box of straws of length 5cm, 7cm and 9cm.

How many different triangles can you make with them?

What if the straws are 3cm, 6cm and 7cm long?

How many different triangles can you make now?

LINE UP THE CLOWNS: YellowRedPinkGreenBlue

MAKING TRIANGLES: With straws that are 5cm, 7cm and 9cm long, you can make 10 different triangles - three equilateral triangles: 5, 5, 5; 7, 7, 7; 9, 9, 9;

six isosceles triangles: 5, 7, 7; 5, 9, 9; 7, 9, 9; 7, 5, 5; 9, 5, 5; 9, 7, 7;

one scalene triangle: 5, 7, 9.

With straws that are 3cm, 6cm, and 7cm long, you can make only 8 triangles. It is impossible to make the isosceles triangles 7, 3, 3 and 6, 3, 3 since the sum of the lengths of two of the sides is less than or equal to the length of the third side.


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