Question

A car covers a distance of 400 km at a certain speed. Had the speed been 12 km/h more, the time taken for the journey would have been 1 hour 40 minutes less. Find the original speed of the car.

it's ok Niki
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Answer 1

Answer:

48 kmph

Step-by-step explanation:

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)

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