Question

1) Some part of a journey of 555 km was completed by a car with speed 60 km/hr. Then the speed is increased by 15 km/hr and the journey is completed. If it takes 8 hours to reach, find the time taken and the distance covered at the speed of 60 km/hr.​

Answer 1

Answer:

Let the time taken by the car be x hours for 60 km/hour and y hours for 75 km/hour.

∴ distance covered by the car with the speed of 60 km/hour = 60x km

Distance covered by the car with the speed of 75 km/hour = 75y km

According to question, we have

x+y=8 ....(i)

60x+75y=555 ....(ii)

⇒15(4x+5y)=555

⇒4x+5y=

15

555

⇒4x+5y=37 ....(iii)

Multiplying (i) by 5, we get

x+y=8 (i)

5x+5y=40 ....(iv)

Subtracting (iii) from (iv), we get

5x+5y=40

4x+5y=37

x=3

∴ time taken by the car at 60 km/hr is 3 hours.

Distance covered by the car with the speed of 60 km/hour = 60×3=180 km