Question

a car covers 30 km at a uniform speed of 30 km per hour what will be its speed for the next 90 km if the average speed for the entire journey is 60 km per hour

Answer 1

Given: total distance= 120 km

Avg. Speed = 60 km/h

Time taken by car to cover 30 km= 30/30= 1 hr

Let the speed of car for next 90km be x

So, the time taken to complete 90 h = 90/x

Now, Avg. Speed = total distance/ total time taken

60 = 120/(1+(90/x))

60(x+90)= 120x

60x + 5400 = 120x

60x = 5400

x = 90 km/h (speed for next 90

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