Australian AMC 2024 - Senior Question 11

Question 11

This design is for part of a quilt. It is based on five overlapping squares of side 10 cm. The darker areas are two identical squares and two identical isosceles triangles. What is the total area of the design?

Question illustration

$350\text{ cm}^2$
$400\text{ cm}^2$
$425\text{ cm}^2$
$450\text{ cm}^2$
$500\text{ cm}^2$