GK 2017 Q7
7. Olivia has 20 euros. Each of her four sisters has 10 euros. How many euros does Olivia need to give to each of her sisters so that each of the five girls has the same amount of money?
- A 2
- B 4
- C 5
- D 8
- E 10
Grey Kangaroo 2017, Question 7. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: A 2
The total amount of the money the five girls have is (20 + 4 × 10) euros = 60 euros. Therefore, if all five girls are to have the same amount, they need to have (60 ÷ 5) euros = 12 euros each. Since each of Olivia's sisters currently has 10 euros, Olivia would need to give each of them (12 − 10) euros = 2 euros.
Solution © UK Mathematics Trust, from the GK 2017 solutions.