To calculate the efficiency of a process, we can use the formula:
\[ \text{Efficiency} = \left( \frac{\text{Useful Energy Output}}{\text{Total Energy Input}} \right) \times 100 \]
Given:
- Useful Energy Output = 250 watts
- Total Energy Input = 850 watts
Substituting the values into the formula:
\[ \text{Efficiency} = \left( \frac{250 \text{ watts}}{850 \text{ watts}} \right) \times 100 \]
Calculating the fraction:
\[ \frac{250}{850} \approx 0.2941 \]
Now, multiplying by 100 to get the efficiency percentage:
\[ \text{Efficiency} \approx 0.2941 \times 100 \approx 29.41% \]
Rounding this value, the efficiency can be considered as approximately 29%.
Thus, the efficiency of the process is 29%.