1. **State the problem:** We need to find how far a unicycle will travel in 4 revolutions if its wheel diameter is 25 inches and radius is 12.5 inches. 2. **Recall the formula:** The distance traveled in one revolution is the circumference of the wheel, given by $$C = 2 \pi r$$ or equivalently $$C = \pi d$$ where $r$ is the radius and $d$ is the diameter. 3. **Calculate the circumference:** Using radius $r = 12.5$ inches, $$C = 2 \pi \times 12.5 = 25 \pi$$ inches. 4. **Calculate distance for 4 revolutions:** $$\text{Distance} = 4 \times C = 4 \times 25 \pi = 100 \pi$$ inches. 5. **Approximate and round:** Using $\pi \approx 3.14159$, $$100 \pi \approx 100 \times 3.14159 = 314.159$$ inches. Rounded to the nearest hundredth, $$314.16$$ inches. **Final answer:** The unicycle will travel approximately **314.16 inches** in 4 revolutions.