Speed, Time and Distance


  1. Starting from his house, one day a student walks at a speed of 3 km/h and reaches his school 5 min late. Next day he increases his speed by 1 km/h and reaches the school 3 min early. How far is the school from his house ?









  1. View Hint View Answer Discuss in Forum

    Let the distance be D km
    Difference in timings = 8 min = 8/60 h = 2/15 h
    ∴ D/3 - D/4 = 2/15

    Correct Option: A

    Let the distance be D km
    Difference in timings = 8 min = 8/60 h = 2/15 h
    ∴ D/3 - D/4 = 2/15
    ⇒ D/12 = 2/15
    ⇒ D = 2 x 12/15 = 1.6 km


  1. If a train runs at 5/6 of its original speed, then it reaches the station 10 min late. Then find out the usual time taken by train to cover the distance.









  1. View Hint View Answer Discuss in Forum

    Assume the actual speed of train be x and actual time taken be y

    And, distance is same in both case

    Correct Option: C

    Let the actual speed of train be x and actual time taken be y

    Then new speed of train = 5x/6

    Therefore, new time taken = 6y/5 (as distance is same in both case)

    Given, 6y/5 - y = 1/6 hr , therefore actual time = 50 min



  1. A car during its journey travels 30 min at a speed of 40 km/h, another 45 min at a speed of 60 km/h and 2 h at a speed of 70 km/h. Find its average speed ?









  1. View Hint View Answer Discuss in Forum

    Average speed = [(30/60) x 40 + (45/60) x 60 + (2 x 70)] / [(30/60) + (45/60) + 2]

    Correct Option: B

    Average speed = [(30/60) x 40 + (45/60) x 60 + (2 x 70)] / [(30/60) + (45/60) + 2]
    = (20 + 45 + 140)/[(30 + 45 + 120)/60]
    = (205/195) x 60 km/h
    = 63.07 km/h
    = 63 km/h


  1. Walking 5/7 of his usual rate, a boy reaches his school 6 min late. Find his usual time to reach the school ?









  1. View Hint View Answer Discuss in Forum

    Since, the boys now walks at 5/7 of usual speed, so he will take 7/5 of his usual time.
    ⇒ Extra time = (7/5 - 1) x Usual time = 6 min (known)

    Correct Option: C

    Since, the boys now walks at 5/7 of usual speed, so he will take 7/5 of his usual time.
    ⇒ Extra time = (7/5 - 1) x Usual time = 6 min (known)
    ⇒ 2/5 x Usual time = 6
    ∴ Usual time = 15 min



  1. Two train leaves New Delhi at the same time. One travels towards North at 60 km/h and the other travels towards South at 40 km/h . After how many hours will the trains be 150 km apart ?









  1. View Hint View Answer Discuss in Forum

    Relative speed = 60 + 40 = 100 km/h

    Correct Option: A

    Relative speed = 60 + 40 = 100 km/h
    Time = Distance/speed = 150/ 00 = 3/2 h