Question

Out of 1900 km, Vishal travelled some distance by bus and some by aeroplane. The bus travels with an average speed of 60 km/hr and the average speed of the aeroplane is 700 km/hr. It takes 5 hours to complete the journey. Find the distance, Vishal travelled by bus.

Answer 1

We know `"speed" = "distance"/"time"`

Average speed of bus = 60km/h.

Let the time taken in bus be x hours. 

Average speed of plane = 700km/h.

Let the time taken in the plane be y hours. 

Total distance covered = 1900 km

60x + 700y = 1900

⇒ 6x + 70y = 190

⇒ 3x + 35y = 95      ...(I)

It takes 5 hours to complete the journey so,

x + y = 5          ...(II)

Multiplying (II) with 3

3x + 3y = 15        ...(III)

Subtracting (III) from (I) we get

3x - 3x + 35y - 3y = 95 - 15

⇒ 32y = 80 

⇒ y = `80/32`

⇒ y = 2.5

Putting the value of y = 2.5 in (II) we get

x + 2.5 = 5

x  = 5 - 2.5

⇒ x = 2.5

Distance travelled by Vishal by bus = speed × time

= 60 × 2.5

= 150 km