GK 2017 Q3
3. The diagram shows two rectangles whose corresponding sides are parallel as shown.
What is the difference between the lengths of the perimeters of the two rectangles?
- A 12 m
- B 16 m
- C 20 m
- D 22 m
- E 24 m
Grey Kangaroo 2017, Question 3. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: E 24 m
The length of the outer rectangle is (3 + 4) m = 7 m longer than the length of the inner rectangle. The height of the outer rectangle is (2 + 3) m = 5 m longer than the height of the inner rectangle. Hence the length of the perimeter of the outer rectangle is (2 × 7 + 2 × 5) m = 24 m longer than the length of the perimeter of the inner rectangle.
Solution © UK Mathematics Trust, from the GK 2017 solutions.