Solving Statement For Upstream And Downstream


 
 
Concept Explanation
 

Solving Statement For Upstream And Downstream

Solving Statements For Upstream and Downstream: In these type of situations, while calculating upstream speed we subtract the speed of river from the speed of boat because the river is pushing the boat downwards even when the boat is moving upwards. Whereas when the boat is moving downstream the speed is calculated by adding the speed of river to the speed of boat.

Example: A boat goes downstream from one point to another in 9 hours. It covers the same distance upstream in 10 hours. If the speed of the stream is 1 km/hr. Calculate the speed of boat in still water.

Solution:     Let the speed of boat in still water be x km/hr

                    Speed of stream  = 1 km/hr

                    Speed upstream = x-1 km/hr

                    Speed Downstream = x + 1 km/hr

                    large speed= frac{distance}{time}

large distance= speed; X ;time

Distance upstream = (x-1) X 10 = 10x - 10 Km

Distance Downstream = (x+1) X 9 = 9x + 9 Km

According to the question the distance is the same

                          10x-10 = 9x + 9

                          10x - 9x = 9+ 10

                                    x = 19 km/hr

So the speed of boat in still watre = 19 km/hr.

Sample Questions
(More Questions for each concept available in Login)
Question : 1

A boat goes downstream from one point to another in 12 hours. It covers the same distance upstream in 15 hours. If the speed of the stream is 1 km/hr. Calculate the speed of boat in still water.

Right Option : B
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Question : 2

A person can row 7frac{1}{2} km/h in still water. It takes him twice as long to row up a distance as to row down the same distance. Find the speed of the stream.

Right Option : C
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Question : 3

A boat can cover 10 km up the stream and 5 km down the stream in 6 hours. If the speed of the stream is 1.5 km/h, find the speed of the boat in still water.

Right Option : B
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