Answer:
The chemical engineer should report average volume of 15.34 L.
Explanation:
Volume of Macon = 0.519 L
Volume of Allegheny = 44.67 L
Volume of Doheny = 0.826 L
Average of the volume of the pollutants:

The rule apply for the addition and subtraction is :
The least precise number present after the decimal point determines the number of significant figures in the answer.
Here the 44.67 has two significant digit after decimal point.So the answer will be reported as in with 2 significant figures after decimal point.

The chemical engineer should report average volume of 15.34 L.