Step 1 :Given the miles per gallon for each truck in the Wellspring Company's fleet: 19, 10, 20, 9, 15, 10, and 23.
Step 2 :To find the mean miles per gallon for the fleet, we need to add all the miles per gallon together and then divide by the total number of trucks.
Step 3 :First, add all the miles per gallon together: \(19 + 10 + 20 + 9 + 15 + 10 + 23 = 106\)
Step 4 :Then, divide the total miles per gallon by the number of trucks: \(\frac{106}{7} = 15.14\)
Step 5 :Round the result to the nearest whole number to get the mean miles per gallon for the fleet.
Step 6 :Final Answer: The mean miles per gallon for the fleet is \(\boxed{15}\) miles per gallon.