Thinking Skills
Zoe, Ali and Ben each have 18 counters. They take turns: showing an even number means give that many to each …
Question 1 · Multiple choice
Question
Zoe, Ali and Ben each have 18 counters. They take turns: showing an even number means give that many to each of the other two; odd means receive that many from each. Zoe spins 2. Ali spins 1. If they end with 15, 24 and 15 respectively (Zoe, Ali, Ben), what did Ben spin?
Options
- A. 1
- B. 2
- C. 3
- D. 4
Correct answer
B. 2
Explanation
After Zoe 2 (even): Zoe gives 2 to each. Zoe 14, Ali 20, Ben 20. After Ali 1 (odd): Ali receives 1 from each. Zoe 13, Ali 22, Ben 19. To reach (15, 24, 15), Ben must give 2 to Zoe and 2 to Ali. This happens when Ben spins 2 (an even number). Zoe 13+2=15, Ali 22+2=24, Ben 19-4=15. So Ben spun 2.