SOLUTION: A goods train leaves a station at 6 p.m. followed by an express train which leaves at 8 p.m and travels 20 km/ hr faster than good train. The express train arrives at a station 104
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Question 959193: A goods train leaves a station at 6 p.m. followed by an express train which leaves at 8 p.m and travels 20 km/ hr faster than good train. The express train arrives at a station 1040 km away, 36 min before the goods train. Find their speeds. Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! Let = the speed of the goods train in km/hr = the speed of the express train in km/hr
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From 6 pm to 8 pm, the goods train gets a
head start of: km
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Start a stopwatch when the express train leaves
Let = the time on the stopwatch when the
express train arrives at station. = time on stopwatch when goods train arrives
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Equation for the goods train:
(1)
Equation for express train:
(2)
---------------------------------
(1)
(1)
(1)
and
(2)
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Substitute (1) into (2)
(2)
(2)
(2)
(2)
(2)
use quadratic formula
and
(2)
(2)
(2)
(2)
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The speed of the goods train is 80 km/hr
The speed of the express train is 100 km/hr
check:
(1)
(1)
(1)
(1)
OK
