SOLUTION: Hi A train passes a 100m platform in 15sec and a man in 10sec .What is the average speed of the train. Thanks

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Question 1152769: Hi
A train passes a 100m platform in 15sec and a man in 10sec .What is the average speed of the train.
Thanks
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the length of the train in meters
Let +s+ = the speed of the train in m/s
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(1) +d+=+s%2A10+
(2) +d+%2B+100+=+s%2A15+
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Plug (1) into (2)
(2) +10s+%2B+100+=+15s+
(2) +5s+=+100+
(2) +s+=+20+
The average speed is 20 m/sec
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get a 2nd opinion if needed