Question

The distance between two places is 120 km a car travelling at a certain speed can cover the distance in 2 hours 30 minutes by how many kilometre per hour should the speed of the car be increased for it to take 30 minutes less to cover the distance

Answer 1

Answer:

Distance = 120km

speed=Distance/time

=120/2.5=48 km/hr

New speed=120/2=60 Km/hr

change inspeed=60-48=12km/hr

Answer 2

Answer:

Distance between two places=120 km

Time= 2 hrs 30 min

        =(2*60)min+30min

        =120min+30min

        =150min=150/60 hr

         = 5/2 hr

Speed = distance /time

           = (120/5/2)km/hr

           =(120×2/5)km/hr

           =(240/5)km/hr

           = 48 km/hr

New time = 2 hr 30min-30min

                = 2hr

Distance =120km

Speed  = Distance /time

            =120/2 km/hr

            = 60 km/hr

Increase in speed=(60-48)km/hr  

                             =12km/hr