Question

What are the gas savings from a 1/5 increase in mileage for a 5400 mile trip, assuming 15 miles per gallon and 35 cents per gallon?

Answer 1

To calculate the gas savings from a 1/5 increase in mileage for a 5400-mile trip, we can break down the problem into several steps.

1. **Current Mileage:**
Given the current mileage is 15 miles per gallon.

2. **Increased Mileage:**
A 1/5 increase in mileage means:
\[
\text{Increase in mileage} = \frac{1}{5} \times 15 \text{ mpg} = 3 \text{ mpg}
\]
So, the new mileage is:
\[
\text{New mileage} = 15 \text{ mpg} + 3 \text{ mpg} = 18 \text{ mpg}
\]

3. **Total Gallons Used:**
Now we will calculate the total gallons of gas used for the trip at both mileages.

- At 15 mpg:
\[
\text{Gallons used} = \frac{5400 \text{ miles}}{15 \text{ mpg}} = 360 \text{ gallons}
\]

- At 18 mpg:
\[
\text{Gallons used} = \frac{5400 \text{ miles}}{18 \text{ mpg}} = 300 \text{ gallons}
\]

4. **Gas Cost Calculation:**
Now we will calculate the cost of the gas used at each mileage, assuming 35 cents per gallon (or $0.35 per gallon).

- Cost at 15 mpg:
\[
\text{Cost} = 360 \text{ gallons} \times 0.35 \text{ dollars/gallon} = 126 \text{ dollars}
\]

- Cost at 18 mpg:
\[
\text{Cost} = 300 \text{ gallons} \times 0.35 \text{ dollars/gallon} = 105 \text{ dollars}
\]

5. **Gas Savings:**
The savings can then be calculated by subtracting the cost at the increased mileage from the cost at the original mileage:
\[
\text{Savings} = 126 \text{ dollars} - 105 \text{ dollars} = 21 \text{ dollars}
\]

Therefore, the gas savings from a 1/5 increase in mileage for a 5400-mile trip is **$21**.