JUNIOR MATHEMATICAL CHALLENGE Thursday 30 April 2020
11. This 3 by 3 grid shows nine 1 cm x 1cm squares and uses 24 cm of wire.
What length of wire is required for a similar 20 by 20 grid?
A 400 cm B 420 cm C 441 cm D 800 cm E 840 cm
12. The diagram shows an equilateral triangle divided into four smaller equilateral
triangles. One of these triangles has itself been divided into four smaller
equilateral triangles.
What fraction of the area of the large triangle has been shaded?
1
3
5
A
B
C
D
E
8
16
16
8
6