Final answer:
The average value of the volunteers' labor per hour, estimated at $1,450 for 135 hours of work, is calculated to be approximately $10.74.
Step-by-step explanation:
To calculate the average value of labor per hour, you need to divide the total estimated fair value of the labor by the total number of hours contributed.
In this scenario, the estimated fair value is $1,450 and the total number of hours contributed is 135 hours. So, the calculation for the average value per hour would be:
\[\frac{\text{Total Estimated Fair Value}}{\text{Total Hours}} = \frac{1450}{135}\]
When calculated, this gives us:
\[\frac{1450}{135} \approx 10.74\]
Therefore, the average value of their labor per hour is approximately $10.74.