Question

28. A man travels a distance of 300 km at a uniform speed. If the speed of the train is increased by 5 km a
lour, the journey would have taken two hours less. Find the original speed of the traain

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Answer 1

Answer:

25km/h

Step-by-step explanation:

total distance=300km

let speed=xkm/hr

therefore time = d/s = 300/x hr---------------1

new speed=x+5 km/hr

therefore time=d/s = 300/x+5 hr-------------2

given difference in times = 2 hrs

therefore from 1 and 2

300/x - 300/x+5 = 2

300x+1500-300x/x(x+5) = 2

1500 = 2xsquare + 10x

2x square + 10x - 1500 = 0

x2 + 5x - 750 = 0

x2 + 30x - 25x -750 =0

x(x+30) - 25(x+30)

(x+30)(x-25)=0

x+30=0       x-25=0    

x= -30         x = 25

 speed cannot be measured in negative

therefore original speed of train is 25 km/hr