Question

a Boat is moving at the rate of 5 kilometre per hour in still water takes 3 as much time in going 40 kilometre upstream and as going 40 kilometre downstream find the speed of the stream​

Answer 1

Answer:

Speed of stream is 2.5 kilometre per hour

Step-by-step explanation:

Speed of boat in still water = 5 km/hr

Let the speed of current be x km/hr

Speed of boat in upstream = (5 - x) km/hr

Speed of boat in downstream = (5 + x) km/hr

Speed, distance and time are related as

Distance = Speed × Time

or Time = Distance/Speed

Given that boat takes 3 as much time in going 40 km upstream as compared to going 40 km downstream

Time taken to go upstream = 3 × Time taken to go downstream

40/(5 - x) = 3 × 40/(5 + x)

1/(5 - x) = 3/(5 + x)

5 + x = 3(5 - x)

5 + x = 15 - 3x

3x + x = 15 - 5

4x = 10

x = 10/4

x = 2.5

Thus, Speed of stream is 2.5 km/hr