Thinking Skills
Ava, Bo and Cal each have 20 marbles. They take turns: showing an even number means give that many to each of…
Question 1 · Multiple choice
Question
Ava, Bo and Cal each have 20 marbles. They take turns: showing an even number means give that many to each of the other two; odd means receive that many from each. Ava spins 4. Bo spins 3. If they end with 8, 29 and 23 respectively (Ava, Bo, Cal), what did Cal spin?
Options
- A. 1
- B. 2
- C. 3
- D. 4
Correct answer
A. 1
Explanation
After Ava 4 (even): gives 4 to each. Ava 12, Bo 24, Cal 24. After Bo 3 (odd): receives 3 from each. Ava 9, Bo 30, Cal 21. To reach (8, 29, 23), Cal must receive 1 from Ava and 1 from Bo. This happens when Cal spins 1 (an odd number). Ava 9-1=8, Bo 30-1=29, Cal 21+2=23. So Cal spun 1.