Question

an aeroplane covers a distance
of 720km with a uniform speed if it's speed is increased by10km/hr it would taken 1hr less to cover the same distance find the speed of aeroplane ​

Answer 1

The speed of the aeroplane is 80 km/hr.

Step-by-step explanation:

Let the speed of the aeroplane is x km/hr.

Now, the time taken by the aeroplane to cover 720 km will be $\frac{720}{x}$ hours.

Given that, if it's speed is increased by 10 km/hr it would take 1 hr less to cover the same distance.

So, we can write the equation as

$\frac{720}{x + 10} = \frac{720}{x} - 1$

⇒ 720x = 720(x + 10) - x(x + 10)

⇒ x² + 10x - 7200 = 0

⇒ x² + 90x - 80x - 7200 = 0

⇒ (x + 90)(x - 80) = 0

So, x = 80 km/hr. {Since, x can not be negative}

Therefore, the speed of the aeroplane is 80 km/hr. (Answer)