Speed, Time and Distance


  1. A constant distance from Chennai to Bangalore is covered by Express train at 100 km/hr. If it returns to the same distance at 80 km/hr, then the average speed during the whole journey is
    1. 90.20 km/hr
    2. 88.78 km/hr
    3. 88.98 km/hr
    4. 88.89 km/hr

  1. View Hint View Answer Discuss in Forum

    If same distance are covered at two different speed of x and y kmph, the average speed of journey

    =
    2xy
    x + y

    =
    2 × 100 × 80
    kmph
    100 + 80

    = 88.89 kmph

    Correct Option: D

    If same distance are covered at two different speed of x and y kmph, the average speed of journey

    =
    2xy
    x + y

    =
    2 × 100 × 80
    kmph
    100 + 80

    = 88.89 kmph


  1. A man travels a distance of 24 km at 6 kmph. Another distance of 24 km at 8 kmph and a third distance of 24 km at 12 kmph. His average speed for the whole journey (in kmph) is
    1. 8
      2
      3
    2. 8
    3. 2
      10
      13
    4. 9

  1. View Hint View Answer Discuss in Forum

    Total distance
    = 24 + 24 + 24 = 72 km.

    Total time
    =
    24
    +
    24
    +
    24
    hours
    6812

    = (4 + 3 + 2) hours = 9 hours
    ∴ Required average speed =
    Total distance
    Total time

    =
    72
    = 8 kmph.
    9

    Correct Option: B

    Total distance
    = 24 + 24 + 24 = 72 km.

    Total time
    =
    24
    +
    24
    +
    24
    hours
    6812

    = (4 + 3 + 2) hours = 9 hours
    ∴ Required average speed =
    Total distance
    Total time

    =
    72
    = 8 kmph.
    9



  1. A train covers a distance of 3584 km in 2 days 8 hours. If it covers 1440 km on the first day and 1608 km on the second day, by how much does the average speed of the train for the remaining part of the journey differ from that for the entire journey ?
    1. 3 km/hour more
    2. 3 km/hour less
    3. 4 km/hour more
    4. 5 km/hour less

  1. View Hint View Answer Discuss in Forum

    Remaining distance
    = (3584 – 1440 – 1608) km
    = 536 km.

    This distance is covered at the rate of
    536
    = 67 kmph.
    8

    Average speed of whole journey
    =
    3584
    = 64 kmph
    56

    ∴  Required difference in speed
    = (67 – 64) kmph i.e. = 3 kmph
    more

    Correct Option: A

    Remaining distance
    = (3584 – 1440 – 1608) km
    = 536 km.

    This distance is covered at the rate of
    536
    = 67 kmph.
    8

    Average speed of whole journey
    =
    3584
    = 64 kmph
    56

    ∴  Required difference in speed
    = (67 – 64) kmph i.e. = 3 kmph
    more


  1. A man goes from A to B at a uniform speed of 12 kmph and returns with a uniform speed of 4 kmph His average speed (in kmph) for the whole journey is :
    1. 8
    2. 7.5
    3. 6
    4. 4.5

  1. View Hint View Answer Discuss in Forum

    If two equal distances are covered at two unequal speed of x kmph and y kmph, then average

    speed =
    2xy
    kmph
    x + y

    =
    2 × 12 × 4
    =
    96
    = 6 kmph
    12 + 416

    Correct Option: C

    If two equal distances are covered at two unequal speed of x kmph and y kmph, then average

    speed =
    2xy
    kmph
    x + y

    =
    2 × 12 × 4
    =
    96
    = 6 kmph
    12 + 416



  1. A man covers half of his journey at 6km/hr and the remaining half at 3km/hr. His average speed is
    1. 9 km/hr
    2. 4.5 km/hr
    3. 4 km/hr
    4. 3 km/hr

  1. View Hint View Answer Discuss in Forum

    If the same distance are covered at different speed of x kmph and y kmph, the average speed of the

    whole journey is given by =
    2xy
    kmph.
    x + y

    ∴  Required average speed =
    2 × 6 × 3
    =
    36
    = 4 kmph
    6 + 39

    Correct Option: C

    If the same distance are covered at different speed of x kmph and y kmph, the average speed of the

    whole journey is given by =
    2xy
    kmph.
    x + y

    ∴  Required average speed =
    2 × 6 × 3
    =
    36
    = 4 kmph
    6 + 39