GK 2015 Q3
3. Four identical small rectangles are put together to form a large rectangle as shown. The length of a shorter side of each small rectangle is 10 cm. What is the length of a longer side of the large rectangle?
- A 50 cm
- B 40 cm
- C 30 cm
- D 20 cm
- E 10 cm
Grey Kangaroo 2015, Question 3. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: B 40 cm
From the diagram, the length of a small rectangle is twice the width. Hence the length of a small rectangle is 20 cm. Therefore the length of the large rectangle, in cm, is 20 + 2 × 10 = 40.
Solution © UK Mathematics Trust, from the GK 2015 solutions.