Question 1147897
Distance (length of train) = d
Rate = 36 kph (difference in speed between the two trains)
Time = 1/90 hour (see explanation below)
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<i>40 seconds = 40 * 1/60 minute = 40/60 minutes = 2/3 minute
2/3 minute = 2/3 * 1/60 hour = 2/180 hours = 1/90 hour</i>
<pr>
We are looking for the distance (length of train), so use the equation: 
<pr>
d = r * t
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d = 36 * 1/90 = 36/90 = 2/5 km
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So, the train is 2/5 km long.