Jen1984 Posted November 13, 2008 Share Posted November 13, 2008 How much time did it take a certain car to travel 400km? (1) The car traveled the first 200km in 2.5 hours. (2) If the car's average speed had been 20km per hour greater than it was, it would have traveled the 400 km in one hour less time than it did. Thanks! Quote Link to comment Share on other sites More sharing options...
spring2009 Posted November 13, 2008 Share Posted November 13, 2008 B........... Quote Link to comment Share on other sites More sharing options...
Jen1984 Posted November 13, 2008 Author Share Posted November 13, 2008 Yes correct but could you explain a little more in details how you got to this result? Quote Link to comment Share on other sites More sharing options...
spring2009 Posted November 13, 2008 Share Posted November 13, 2008 1) we don't know the speed of the last 200km 2) If the car's average speed had been 20km per hour greater than it was, it would have traveled the 400 km in one hour less time than it did. We can understand as: speed2 = speed1 + 20 time2 = time1 - 1 => 400/t2 = 400/t1 +20 and t2 = t1 - 1 => Aren't we able to find t1? Quote Link to comment Share on other sites More sharing options...
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