Question

A man covers a distance of 64.8 kilometre by car in 2 hours and 172.8 kilometre by train in 4 hours find the average speed of his journey.​

Answer 1

Step-by-step explanation:

Let the original speed of car is x km \hr

Then time taken in moving 840 km=

x

840

hr

if speed is going 10 km \hr more =x+10

Then time taken in moving 840 km=

x+10

840

hr

∴

x

840

−

x+10

840

=2

⇒840(x+10)−840x=2x(x+10)

⇒2x

2

+20x−8400=0

⇒x

2

+70x+−60x−4200=0

⇒(x+70)(x−60)=0

⇒x=60orx=−70

If x=-70 is not true because speed not negetive

So speed is 60 km \ hr