Question

A car covers a distance of 715 km at a constant speed .if the speed of the car would have been 10 km/hr more,then it would have taken 2 hrs less to cover same distance .what is the original speed of the car

Answer 1

Answer:

The original speed of the car is 55 km/s.

Explanation:

Given that,

Total distance = 715 km

Speed = 10 km/h

Time  = 2 hr

Suppose the original speed of the car is x

The speed of the car is equal to the distance divided by the time.

$v = \dfrac{d}{t}$

The initial time t is

$t = \dfrac{715}{x}$....(I)

If the speed of the car would have been 10 km/hr more.

The time will be

$T = \dfrac{715}{x+10}$....(II)

Then it would have taken 2 hrs less to cover same distance.

Then, The original speed of the car is

$t -T=2$

$\dfrac{715}{x}- \dfrac{715}{x+10}=2$

$2x^2+20x-7150=0$

$x = 55\ km/s$

On neglect the negative value.

Hence, The original speed of the car is 55 km/s.