Speed of boat in still water from speed of stream and times taken - GeeksforGeeks

15 Apr, 2021
Write a program to determine speed of the boat in still water(B) given the speed of the stream(S in km/hr), the time taken (for same point) by the boat upstream(T1 in hr) and downstream(T2 in hr).
Examples: 
Input : T1 = 4, T2 = 2, S = 5
Output : B = 15

Input : T1 = 6, T2 = 1, S = 7
Output : B = 9.8  
Prerequisite : Speed of boat upstream and downstreamSpeed of boat in still water can be computed using below formula. B = S*((T1 + T2) / (T1 – T2))
How does this formula work? Since the point is same, distance traveled during upstream should be same as downstream. Therefore, (B – S) * T1 = (B + S) * T2 B(T1 – T2) = S*(T1 + T2) B = S*(T1 + T2)/(T1 – T2)
C++
Java
Python3
C#
PHP
Javascript
// CPP program to find speed of boat in still water// from speed of stream and times taken in downsteam// and upstream#include <iostream>using namespace std; // Function to calculate the speed of boat in still waterfloat still_water_speed(float S, float T1, float T2){    return (S * (T1 + T2) / (T1 - T2));} int main(){    float S = 7, T1 = 6, T2 = 1;    cout << "The speed of boat in still water = "<<             still_water_speed(S, T1, T2)<<" km/ hr ";    return 0;}
// Java program to find speed of boat in still water// from speed of stream and times taken in downsteam// and upstreamimport java.io.*; class GFG{    // Function to calculate the    // speed of boat in still water    static float still_water_speed(float S, float T1, float T2)    {        return (S * (T1 + T2) / (T1 - T2));    }     // Driver code    public static void main (String[] args) {        float S = 7, T1 = 6, T2 = 1;        System.out.println("The speed of boat in still water = "+                            still_water_speed(S, T1, T2)+" km/ hr ");         }} // This code is contributed by vt_m.
# Python3 program to find speed of boat# in still water from speed of stream and# times taken in downsteam and upstream # Function to calculate the# speed of boat in still waterdef still_water_speed(S, T1, T2):    return (S * (T1 + T2) / (T1 - T2))     # Driver codeS = 7; T1 = 6; T2 = 1print("The speed of boat in still water = ",       still_water_speed(S, T1, T2), " km/ hr ")        # This code is contributed by Anant Agarwal.
// C# program to find speed of boat// in still water from speed of stream// and times taken in downsteam// and upstreamusing System; class GFG {         // Function to calculate the    // speed of boat in still water    static float still_water_speed(float S, float T1,                                            float T2)    {        return (S * (T1 + T2) / (T1 - T2));    }     // Driver code    public static void Main()    {        float S = 7, T1 = 6, T2 = 1;        Console.WriteLine("The speed of boat in still water = " +                      still_water_speed(S, T1, T2) + " km/ hr ");    }} // This code is contributed by vt_m.
<?PHP// PHP program to find speed of// boat in still water from speed// of stream and times taken in// downsteam and upstream // Function to calculate the speed// of boat in still waterfunction still_water_speed($S, $T1, $T2){    return ($S * ($T1 + $T2) /                 ($T1 - $T2));} // Driver Code$S = 7;$T1 = 6;$T2 = 1;echo("The speed of boat in still water = " .           still_water_speed($S, $T1, $T2) .                                " km/hr "); // This code is contributed by Smitha?>
<script> // Javascript program to find speed of// boat in still water from speed// of stream and times taken in// downsteam and upstream   // Function to calculate the speed// of boat in still waterfunction  still_water_speed(S, T1, T2){    return (S * (T1 + T2) / (T1 - T2));}   // Driver Codevar S = 7;var T1 = 6;var T2 = 1;document.write("The speed of boat in still water = " +               still_water_speed(S, T1, T2) + " km/hr ");                // This code is contributed by bunnyram19 </script>
Output: 
The speed of boat in still water = 9.8 km/hr
 
Smitha Dinesh Semwal
bunnyram19
Time Speed Distance
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