SOLUTION: A train was late by 3 hours.It had to cover a distance of 900 km. To cover the time, the driver increased the speed by 15 kmph.Find the increased speed of the train
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Question 698362: A train was late by 3 hours.It had to cover a distance of 900 km. To cover the time, the driver increased the speed by 15 kmph.Find the increased speed of the train
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Call the increased speed
With speed , time is
where is on time
---------------------
Equation being late by 3 hrs:
(1)
Equation for being on time:
(2)
-----------------------
(1)
(1)
(1)
Substitute (1) into (2)
(2)
(2)
(2)
(2)
(2)
Use quadratic formula
( ignore the (-) square root )
The increased speed of the train is 75 km/hr
check:
(1)
(1)
(1)
and
(2)
(2)
(2)
OK
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