Question

6.26 LAB: Driving cost - methods

Write a method drivingCost() with input parameters drivenMiles, milesPerGallon, and dollarsPerGallon, that returns the dollar cost to drive those miles. All items are of type double. If the method is called with 50 20.0 3.1599, the method returns 7.89975.

Define that method in a program whose inputs are the car's miles/gallon and the gas dollars/gallon (both doubles). Output the gas cost for 10 miles, 50 miles, and 400 miles, by calling your drivingCost() method three times.

Output each floating-point value with two digits after the decimal point, which can be achieved as follows:
System.out.printf("%.2f", yourValue);

The output ends with a newline.

Ex: If the input is:

20.0 3.1599

the output is:

1.58 7.90 63.20

Your program must define and call a method:
public static double drivingCost(double drivenMiles, double milesPerGallon, double dollarsPerGallon)

Note: This is a lab from a previous chapter that now requires the use of a method.

Answer 1

Program

import java.util.Scanner;

public class cost_driving {

    

    /* Method definition */

    public static double drivingCost(double drivenMiles, double milesPerGallon, double dollarsPerGallon) {

        double totalCost = (dollarsPerGallon * drivenMiles / milesPerGallon);

        return totalCost;

    }

    

    public static void main(String[] args) {

        Scanner scnr = new Scanner(System.in);

        System.out.print("Enter miles per gallon: ");

        double milesPerGallon = scnr.nextDouble();

        System.out.print("Enter dollars per gallon: ");

        double dollarsPerGallon = scnr.nextDouble();

        double drivenMiles = 1;

        System.out.printf("\nGas cost for 10 miles = %.2f ", drivingCost(drivenMiles, milesPerGallon, dollarsPerGallon) * 10);

        System.out.printf("\nGas cost for 50 miles = %.2f ", drivingCost(drivenMiles, milesPerGallon, dollarsPerGallon) * 50);

        System.out.printf("\nGas cost for 400 miles = %.2f\n", drivingCost(drivenMiles, milesPerGallon, dollarsPerGallon) * 400);

    }

}

Output

Enter miles per gallon: 20
Enter dollars per gallon: 3.1599

Gas cost for 10 miles = 1.58
Gas cost for 50 miles = 7.90
Gas cost for 400 miles = 63.20