Examples

Chapter 13 Class 8 Direct and Inverse Proportions
Serial order wise

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Example 4 A train is moving at a uniform speed of 75 km/hour. (i) How far will it travel in 20 minutes? Given, Train is moving at a uniform speed of 75 km/hour β΄ Distance travelled by train in 1 hour = 75 km i.e. Distance travelled by train in 60 minutes = 75 km We need to find how far will the train travel in 60 minutes Let train travel x km Thus, our table looks like Now, as distance increases time taken to travel also increases β΄ They are in direct proportion. 75/60 = π₯/20 75/60 Γ 20= π₯ 75/3 = π₯ 25 = π₯ π₯ = 25 km β΄ Train will travel 25 km Example 4 A train is moving at a uniform speed of 75 km/hour. (ii) Find the time required to cover a distance of 250 km. We need to find time required to cover a distance of 250 km Let time required be y minutes Thus, our table looks like Since distance and time are in direct proportion 75/60 = 250/π¦ 75 Γ y = 60 Γ 250 π¦ = (60 Γ 250)/75 π¦ = (4 Γ 250)/5 π¦ = (4 Γ 50)/1 π¦ = 200 minutes Converting to hours π¦ = 200/60 hours π¦ = 3 hours 20 min β΄ Train will require 3 hours 20 minutes