SOLUTION: When a train travels at 5/8 of its real speed it takes 1 hr 12 minutes more than the actual time if travelled at the real speed.The actual time to be taken to reach the destination

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Question 1043092: When a train travels at 5/8 of its real speed it takes 1 hr 12 minutes more than the actual time if travelled at the real speed.The actual time to be taken to reach the destination is = ?
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Use the formula d+=+rt for the distance travelled by an object with speed r for an interval of time t.
Let the real speed of the train be r. Suppose the the distance to the destination is d. 5/8 of its real speed is %285%2F8%29r,
and the time travelled would be +d%2F%28%285%2F8%29r%29+=+%288%2F5%29%28d%2Fr%29. Hence,
+%288%2F5%29%28d%2Fr%29+-+d%2Fr+=+6%2F5,
since 1 hour, 20 minutes is 1%261%2F5+=+6%2F5 hours.
===> %283%2F5%29%28d%2Fr%29+=+6%2F5 ===> d%2Fr+=+2, or d = 2r.
===> The actual time taken to reach the destination is t+=+d%2Fr+=+%282r%29%2Fr+=+highlight%282%29 hours.