Final answer:
To determine the cost difference per mile to run a car before and after a mechanic's work, we find the cost per mile before ($0.0941/mile) and the cost per mile after the work ($0.0800/mile), then calculate the difference, resulting in approximately $0.0141 less per mile after the mechanic's work.
Step-by-step explanation:
The question requires us to calculate the cost difference per mile to run a car before and after a mechanic worked on it. To do this, we will compute the cost per mile before and after the mechanic's work and then find the difference between the two.
First, let's find the cost per mile before the mechanic's work:
- Miles driven: 340 miles
- Gallons used: 8 gallons
- Cost per gallon: $4.00
Cost per mile before mechanic's work = (8 gallons * $4.00) / 340 miles = $0.0941/mile (rounded to the nearest cent)
Now, let's find the cost per mile after the mechanic's work:
- Miles driven: 350 miles
- Gallons used: 7 gallons
- Cost per gallon: $4.00
Cost per mile after mechanic's work = (7 gallons * $4.00) / 350 miles
= $0.0800/mile (rounded to the nearest cent)
To find how much less it costs per mile after the mechanic's work, we subtract the before cost per mile from the after cost per mile:
Difference in cost per mile = $0.0941/mile - $0.0800/mile
= $0.0141/mile
The cost to run the car after the mechanic's work was approximately $0.0141 less per mile.