Question 868436: car takes 3 hours to complete a journey going at a speed of 90 km per hr. How long will it take to do the same journey if it travels at 120 km per hr?
Answer by JLJL(8)   (Show Source):
You can put this solution on YOUR website! Using the formula, distance = speed X time
Given that the car takes 3 hours to complete a journey at the speed of 90km/hr. That means the total distance of the journey = 90km/hr X 3 hr, which will give 270km.
To travel for the same distance with increased speed, i.e, 120km/hr. Replace 90km/hr with 120km/hr but maintain 270km (because the car is traveling for the same distance again)into the same formula again.
distance = speed X time
270km = (120km/hr) X time
time = (270km)/(120km/hr)
time = 9/4 hr
This means if the car travel at 120km/hr for the same distance, the car will take 9/4 hour (9/4 could be re-written in form of mixed number, 2/1/4 hours, means 2 hours and 15 minutes) to complete the journey.
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