Find the speed of the stream from the speed of the man given in both upstream and downstream

Last Updated : 19 Feb, 2022

A boat takes N1 hr to row a bot X1 km downstream of a river and take N2 hr to cover a distance of X2 km upstream. Find the speed of the stream.

Input: 3 15 2 5
Output: 17.5 km/hr

Input: 4 29 7 30
Output: 47 km/hr

Approach:

  • Take input from users
  • Calculate the rate of downstream and upstream. The rate can be calculated using the formula.

Speed = \frac{distance}{time}

  • Then, calculate the speed of the stream. It is given by the formula -

Rate of Stream = \frac{1}{2}(downstream - upstream)  

Below is the implementation. 

C++ 
#include<iostream>
using namespace std;

void rate(float down, float up)
{
    
    // Stream rate
    float rate = 0.5 * (down - up);
    cout << rate <<  " Km/hr";
}

// Driver Code
int main()
{
  
    // Distance and time downstream
    float N1 = 3;
    float X1 = 15;

    // Distance and time upstream
    float N2 = 2;
    float X2 = 5;

    // Rate of downstream and upstream
    float Rate_downstream = X1 / N1;
    float Rate_upstream = X2 / N2;

    rate(Rate_downstream, Rate_upstream);
   
   return 0;
}

// This code is contributed by Surbhi Tyagi.
Java 
/*package whatever //do not write package name here */

import java.io.*;

public class GFG
{
    
public static void rate(float down, float up)
{
    
    // Stream rate
    double rate = 0.5 * (down - up);
    System.out.println(rate+ " Km/hr");
}
 
// Driver Code
public static void main(String args[])
{
  
// Distance and time downstream
float N1 = 3;
float X1 = 15;

// Distance and time upstream
float N2 = 2;
float X2 = 5;

// Rate of downstream and upstream
float Rate_downstream = X1 / N1;
float Rate_upstream = X2 / N2;

rate(Rate_downstream, Rate_upstream);
    }
}

// This code is contributed by sravankumar8128.
Python3 
def rate(down, up):

    # stream rate
    rate = 0.5*(down - up)
    print(rate, " Km/hr")


# Driver Code
# Distance and time downstream
N1 = 3
X1 = 15

# Distance and time upstream
N2 = 2
X2 = 5

# Rate of downstream and upstream
Rate_downstream = X1/N1
Rate_upstream = X2/N2

rate(Rate_downstream, Rate_upstream)
JavaScript 
<script>

function rate(down, up)
{
    
    // Stream rate
    var rate = 0.5 * (down - up);
    document.write(rate, " Km/hr");
}
 
// Driver Code

// Distance and time downstream
var N1 = 3;
var X1 = 15;

// Distance and time upstream
var N2 = 2;
var X2 = 5;

// Rate of downstream and upstream
var Rate_downstream = X1 / N1;
var Rate_upstream = X2 / N2;

rate(Rate_downstream, Rate_upstream);

// This code is contributed by Ankita saini
                    
</script>
C# 
// C# program for the above approach
using System;
class GFG {

    static double rate(float down, float up)
    {

        // Stream rate
        double rate = 0.5 * (down - up);
        return rate;
    }

    // Driver Code
    public static void Main()
    {
        // Distance and time downstream
        float N1 = 3;
        float X1 = 15;

        // Distance and time upstream
        float N2 = 2;
        float X2 = 5;

        // Rate of downstream and upstream
        float Rate_downstream = X1 / N1;
        float Rate_upstream = X2 / N2;

        Console.WriteLine(
            rate(Rate_downstream, Rate_upstream)
            + " Km/hr");
    }
}

// This code is contributed by Palak Gupta

Output:

1.25  Km/hr

Time Complexity: O(1)

Auxiliary Space: O(1)
 

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