Question

An aeroplane takes 1 hour less for a journey of 1200 km if its speed is increased by 100 km/hr from its usual speed. Find its usual speed.

Answer 1

Now, speed is increased by 100 km/hr and the time has taken is 1 hour less for the same journey.

⇒ Speed of the plane after increased = (x +100) km/hr and Time is taken by plane with

Since speed cannot be negative so, x = 300 ∴ usual speed of the plane = 300 km/hr