18 thoughts on “Time, Speed and Distance – 2

  1. Dearest J,
    Please elucidate the last statement of 2nd question’s sol.
    If they are 15km apart in the last hour then…I couldn’t digest the part after it.

    • Imagine their journey is recorded and played _backwards_ from the point of their meeting. They would be moving _away_ from each other at 15 kmph. Now tell me, how far apart would they be in a minute?.

      regards
      J

  2. An easier solution to the second problem could be as follows:
    Required: distance between them 1 minute prior to collision

    This is equal to= Distance travelled by first boat in 1 minute + dist travelled by second boat in 1 minute
    = 5/60 + 10/60 = 15/60 = 1/4 km apart

  3. Dear J,
    In the first question, how did you arrive at the conclusion that car 1 and car 2 have a time difference of one hour at their first meeting? They reach simultaneously right?

  4. Ipsy, you are right, they arrive simultaneously. But see the question – they start one hour apart! One at 7 am and one at 8. Hence the one starting at 7 will have been traveling for an hour longer….

    regards
    J

    • Possible, but not probable Girish 🙂 You know my schedule… besides, most of arithmetic tends to be on the easy side and I don’t see any significant value-add I can offer in those questions. If I think of something I will definitely post!

      regards
      J

  5. Dear J, Is there a trick to solve following type of Question :
    Gaurav starts running along a straight line at uniform speed from point A to point B, which is located at a distance of 3000 m from point A. At the same instant, his pet dog starts running from point B to point A at a speed twice that of Gaurav. After the dog meets Gaurav at a point between A and B, the dog reverses his direction and starts running towards point B. On reaching point B, the dog again reverses his direction and meets Gaurav. On meeting Gaurav, the dog again reverses his direction and starts running towards point B. This process continues till Gaurav reaches point B. What is the distance run by the dog in the direction opposite to Gaurav (in meters)?

  6. Dear J,
    Can you help me with the short way/ Trick to solve following type of problem:
    Gaurav starts running along a straight line at uniform speed from point A to point B, which is located at a distance of 3000 m from point A. At the same instant, his pet dog starts running from point B to point A at a speed twice that of Gaurav. After the dog meets Gaurav at a point between A and B, the dog reverses his direction and starts running towards point B. On reaching point B, the dog again reverses his direction and meets Gaurav. On meeting Gaurav, the dog again reverses his direction and starts running towards point B. This process continues till Gaurav reaches point B. What is the distance run by the dog in the direction opposite to Gaurav (in meters)?

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