Problem 3 · Combine moves, then discard full laps · 3 points
Made by AI and not reviewed by a real person.
A toy starts on space 1 of a circular board numbered 1 to 8 clockwise. Each dance moves it 5 spaces clockwise, then 2 spaces counterclockwise; where is it after 47 dances?

- 6
- 5
- 4
- 2
- 3
Show a hint
- Think about where one complete dance leaves the toy compared with where it began. What happens when it makes a full lap?
- Each dance moves the toy 3 spaces clockwise overall. How many full laps can you ignore after 47 dances?
Show the answer and solution
Answer: A — 6
Each dance moves the toy 5 − 2 = 3 spaces clockwise. After 47 dances, that is 47 × 3 = 141 spaces. Since 141 = 17 × 8 + 5, the toy finishes 5 spaces clockwise from 1, on space 6. Space 4 is tempting if you count the clockwise moves but forget that every dance also moves the toy backward.