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Pieces of Eight
Age
11 to 14
Short
Challenge Level
Secondary curriculum
Problem
Solutions
A square is divided into eight congruent triangles, as shown.
Two of these triangles are selected at random and shaded black.
What is the probability that the resulting figure has at least one line of symmetry?
If you liked this problem,
here is an NRICH task
that challenges you to use similar mathematical ideas.
This problem is taken from the
UKMT Mathematical Challenges
.
You can find more short problems, arranged by curriculum topic, in our
short problems collection
.