Speed, Time and Distance


  1. A thief is spotted by a policeman from a distance of 200 m. When the policeman starts chasing, the thief also starts running. If the speed of the thief be 16 km/h and that of the policeman be 20 km/h, how far the thief will have run before he is overtaken?









  1. View Hint View Answer Discuss in Forum

    Relative speed of policeman = ( 20 - 16 ) x 5/18 = 10/9 m/s
    To catch the thief, the policeman in has to gain 200 m = 200 x 9/10 = 180 s

    Correct Option: A

    Relative speed of policeman = ( 20 - 16 ) x 5/18 = 10/9 m/s
    To catch the thief, the policeman in has to gain 200 m = 200 x 9/10 = 180 s
    Actual distance covered by policeman in 180 s = 180 x 50/9 = 100 m
    ∴ Distance covered by the thief = 1000 - 200 = 800m


  1. Two men A and B travel from point P to Q, a distance of 84 km at 12 km/h and 16 km/h, respectively. B reaches Q and returns immediately and meet A at R. Find the distance form P to R.









  1. View Hint View Answer Discuss in Forum

    Given, D = 84 km, a = 12 km/h and b = 16 km/ h
    According to the formula
    Distance traveled by A = PR = 2D x a/(a + b)

    Correct Option: A

    Given, D = 84 km, a = 12 km/h and b = 16 km/ h
    According to the formula
    Distance traveled by A = PR = 2D x a/(a + b)
    = 2 x 84 x 12/(12 + 16) = (2 x 84 x 12)/28
    = 2 x 6 x 6 = 72 km



  1. A person can walk a certain distance and drive back in 6 h. He can also walk both ways in 10 h. How much time will he take to drive both ways?









  1. View Hint View Answer Discuss in Forum

    Given that, W + D = 6 ...(i)
    [ w = Time taken while walking and
    D = Time taken while driving ]
    From Eq. (i)
    5 +D = 6
    ⇒ D = 1

    Correct Option: A

    Given that, W + D = 6 ...(i)
    [ w = Time taken while walking and
    D = Time taken while driving ]
    From Eq. (i)
    5 +D = 6
    ⇒ D = 1
    2D = 2 x 1 = 2
    ∴ He will take 2 h to drive both ways.


  1. Rani covers a certain distance by car driving at 5 km/h and returns the starting point riding on a scooter at 2 km/h. Find her average speed for the whole journey.









  1. View Hint View Answer Discuss in Forum

    According to the formula,
    Average speed = 2AB/(A + B)

    Correct Option: B

    According to the formula,
    Average speed = 2AB/(A + B)
    Here, A = 5 km/h, and B = 2 km/h
    ∴ Required average speed = (2 x 5 x 2)/7 = 20/7
    = 26/7 km/h



  1. A bullock cart has to cover a distance of 80 km in 10 h. If it covers half of the journey in 3/5th time, what should be its speed to cover the remaining distance in the left time?









  1. View Hint View Answer Discuss in Forum

    Total distance to covered in 10 h = 80 km
    But it covers 40 km in 3/5th of time, i.e, 40 km in 6 h.
    ∴ Required time = 10 - 6 = 4 h
    And remaining distance = 40 km

    Correct Option: B

    Total distance to covered in 10 h = 80 km
    But it covers 40 km in 3/5th of time, i.e, 40 km in 6 h.
    ∴ Required time = 10 - 6 = 4 h
    And remaining distance = 40 km
    Thus, required speed = 40/4 =10 km/h