Speed, Time and Distance


  1. A train travelled at a speed of 35 km/hr for the first 10 minutes and at a speed of 20 km/hr for the next 5 minutes. The average speed of the train for the total 15 minutes is
    1. 30 km/hr
    2. 23 km/hr
    3. 31 km/hr
    4. 29 km/hr

  1. View Hint View Answer Discuss in Forum

    Distance covered = 35 ×
    10
    + 20 ×
    5
    km
    6060

    =
    35
    +
    10
    km
    66

    =
    45
    km
    6

    Total time = 15 minutes
    =
    1
    hour
    4

    ∴  Required average speed =
    Distance covered
    Time taken

    =
    45
    × 4
    6

    = 30 kmph

    Correct Option: A

    Distance covered = 35 ×
    10
    + 20 ×
    5
    km
    6060

    =
    35
    +
    10
    km
    66

    =
    45
    km
    6

    Total time = 15 minutes
    =
    1
    hour
    4

    ∴  Required average speed =
    Distance covered
    Time taken

    =
    45
    × 4
    6

    = 30 kmph


  1. A bus covers four successive 3 km stretches at speed of 10 km/hr, 20 km/hr, 30 km/hr and 60 km/hr respectively. Its average speed over this distance is
    1. 30 km/hr
    2. 25 km/hr
    3. 20 km/hr
    4. 10 km/hr

  1. View Hint View Answer Discuss in Forum

    Average speed =
    Total distance
    Time taken

    =
    12
    3
    +
    3
    +
    3
    +
    3
    10203060


    =
    12
    3
    6 + 3 + 2 + 1
    60

    =
    12 × 60
    = 20 kmph
    3 × 12

    Correct Option: C

    Average speed =
    Total distance
    Time taken

    =
    12
    3
    +
    3
    +
    3
    +
    3
    10203060


    =
    12
    3
    6 + 3 + 2 + 1
    60

    =
    12 × 60
    = 20 kmph
    3 × 12



  1. With an average speed of 40 km/hr, a train reaches its destination in time. If it goes with an average speed of 35 km/hr, it is late by 15 minutes. The total journey is
    1. 30 km
    2. 40 km
    3. 70 km
    4. 80 km

  1. View Hint View Answer Discuss in Forum

    Let the length of journey be x km, then

    x
    x
    =
    15
    =
    1
    3540604

    ⇒ 
    8x − 7x
    =
    1
    2804

    ⇒  x =
    280
    = 70 km
    4

    Correct Option: C

    Let the length of journey be x km, then

    x
    x
    =
    15
    =
    1
    3540604

    ⇒ 
    8x − 7x
    =
    1
    2804

    ⇒  x =
    280
    = 70 km
    4


  1. P travels for 6 hours at the rate of 5 km/ hour and for 3 hours at the rate of 6 km/ hour. The average speed of the journey in km/ hour is
    1. 3
      1
      5
    2. 5
      1
      3
    3. 1
      2
      9
    4. 2
      2
      5

  1. View Hint View Answer Discuss in Forum

    Total distance
    = 5 × 6 + 3 × 6
    = 30 + 18 = 48 km
    Total time = 9 hours

    ∴ Average speed =
    48
    =
    16
    = 5
    1
    kmph
    933

    Correct Option: B

    Total distance
    = 5 × 6 + 3 × 6
    = 30 + 18 = 48 km
    Total time = 9 hours

    ∴ Average speed =
    48
    =
    16
    = 5
    1
    kmph
    933



  1. A man covers the journey from a station A to station B at a uniform speed of 36 km/hr and
    returns to A with a uniform speed of 45 km/hr. His average speed for the whole journey is :
    1. 40 km/hr
    2. 40.5 km/hr
    3. 41 km/hr
    4. 42 km/hr

  1. View Hint View Answer Discuss in Forum

    Here same distances are covered at different speeds.

    ∴  Average speed =
    2xy
    kmph
    x + y

    =
    2 × 36 × 45
    kmph
    (36 + 45)

    =
    2 × 36 × 45
    = 40 kmph
    81

    Correct Option: A

    Here same distances are covered at different speeds.

    ∴  Average speed =
    2xy
    kmph
    x + y

    =
    2 × 36 × 45
    kmph
    (36 + 45)

    =
    2 × 36 × 45
    = 40 kmph
    81