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 km/h should the speed of the car be increased for it to take 30 minutes less to cover the distance?
2 answers:
Answer:
Distance between two places=120 km
Step-by-step explanation:
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
Another way to show :
Distance = 120km
speed=Distance/time
=120/2.5=48 km/hr
New speed=120/2=60 Km/hr
change inspeed=60-48=12km/hr
Distance = 120 km
Time = 2hr 30min
speed = distance/ time
Average speed = 120/ 2.5 because 2h r30min = 2.5 hrs
120/2.5 = 48km/h
2hr30min - 30min = 2hrs
120/2 = 60km/h
=> (60–48)km/h = 12km/h
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