Question

aqar cover a distance of 400
km at a certain speed had the speed been 12 kilometre per hour more the time taken for the journey would have been 1 hour 40 minutes less find the original speed of the car

Answer 1

Answer:

Let the original speed of the car be x kmph

case i:

Distance = 400 km

speed = x kmph

Time taken = 400/x hrs

case ii:

Distance = 400 km

speed = (x+12) kmph

Time taken = (400/x+12)

But as per the question, the time taken is 1 hr 40 min lesser than the previous.

that means,

400/x - (1 hr 40 min) = (400/x+12)

400/x -5/3  = 400/x+12

1200-5x/3x = 400/ x+12

1200x - 5x^2 + 14400 - 60x = 1200x

x² + 12x - 2880 = 0

(x - 48)(x + 60)  = 0

x = 48 as the negative value of x is ignored.

The original speed of the car = 48 kmph