GK 2015 Q5
5. A triangle has sides of lengths 6 cm, 10 cm and 11 cm. An equilateral triangle has the same perimeter. What is the length of the sides of the equilateral triangle?
- A 18 cm
- B 11 cm
- C 10 cm
- D 9 cm
- E 6 cm
Grey Kangaroo 2015, Question 5. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: D 9 cm
The perimeter of the equilateral triangle is (6 + 10 + 11) cm = 27 cm. Hence the length of the sides of the equilateral triangle is 27 cm ÷ 3 = 9 cm.
Solution © UK Mathematics Trust, from the GK 2015 solutions.