How many rotations will the hour hand of a clock complete in 72 hours?

### Concept & Clock Rotations A standard analog clock is divided into 12 hours. Therefore, the hour hand completes exactly one full 360-degree rotation every 12 hours. ### Step-by-Step Solution 1. **Given:** Total time period = 72 hours. 2. We know that 1 rotation of the hour hand = 12 hours. 3. To find the number of rotations in 72 hours, divide the total hours by the hours per rotation: $$\text{Rotations} = \frac{72}{12}$$ 4. $$72 \div 12 = 6$$ rotations. ### Exam Strategy & Shortcut Memorize standard day conversions: 24 hours = 2 rotations of the hour hand (1 full day). Since 72 hours is exactly 3 days, multiply 2 rotations/day by 3 days = 6 rotations. ### Common Pitfall Confusing the hour hand with the minute hand or the Earth's rotation. The hour hand rotates twice a day (every 24 hours), not once! ### Final Answer Therefore, the correct answer is **6**.