Question

Suppose a gas company bases its charges on consumption according to the following table:

Gas Charges

Gas Used	Rate
First 70 cubic meters	$5.00 minimum cost
Next 100 cubic meters	$0.05 per cubic meter
Next 230 cubic meters	$0.025 per cubic meter
Above 400 cubic meters	$0.015 per cubic meter

Write a program in C++ that asks the user to enter the number of cubic meters of gas used, calculates the charges, and displays the total charge.

Answer 1

// C++ program that asks the user to enter the number of cubic meters of gas used, calculates the charges, and displays the total charge.

#include <iostream>

using namespace std;

int main()
{
double gasUsed, charges;

// input the number of cubic meters of gas used
cout<<"Enter the number of cubic meters of gas used: ";
cin>>gasUsed;

charges = 5; // set charges to base charge of 5
gasUsed -= 70; // subtract first 70 cubic meters from gasUsed

// initial gasUsed > 70
if(gasUsed > 0){
// next 100 cubic meters is charged at $0.05 per cubic meter
if(gasUsed > 100) // gasUsed > 100
charges += 100*0.05; // add charges for next 100
else // add charges for the left gas
charges += (gasUsed)*0.05;
gasUsed -= 100; // subtract 100 from gas used
}

// initial gasUsed > 170
if(gasUsed > 0)
{
// next 230 cubic meters is charged at $0.025 per cubic meter
if(gasUsed > 230) // gasUsed > 230
charges += 230*0.025; // add charges for next 230
else // add charges fro left gas
charges += gasUsed*0.025;
gasUsed -= 230; // subtract 230 from gas used
}

// initial gasUsed > 400
if(gasUsed > 0)
{
// above 400 cubic meters is charged at $0.015 per cubic meter
charges += gasUsed*0.015; // add charges for left gas
}

// display the charges to 2 decimal places
cout<<fixed;
cout.precision(2);

cout<<"Total charge: $"<<charges<<endl;
return 0;
}

//end of program

Output: