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. A person sets out to cycle from A to B and at the same time another person starts from B to A. After passing each other, they complete their journeys in 16 h and 25 h, respectively. Find the ratio of speeds of the 1st man to that of the 2 nd man.









  1. View Hint View Answer Discuss in Forum

    Given, x = 16 and Y = 25
    According to the formula,
    1st man's speed : 2nd man's speed = √ y : √ x

    Correct Option: A

    Given, x = 16 and Y = 25
    According to the formula,
    1st man's speed : 2nd man's speed = √ y : √ x = √ 25 : √ 16 = 5 : 4



  1. A certain distance is covered at a certain speed. If half of this distance is covered in 4 times of the time, then find the ratio of the two speeds.?









  1. View Hint View Answer Discuss in Forum

    Let L km is covered in T h.
    Then, first speed = L/T km/h
    Again, L/2 km is covered in 4T h.
    ∴ New speed = (L/2 x 1/4T ) = (L/8T) km/ h

    Correct Option: D

    Let L km is covered in T h.
    Then, first speed = L/T km/h
    Again, L/2 km is covered in 4T h.
    ∴ New speed = (L/2 x 1/4T ) = (L/8T) km/ h
    Ratio of speed = L/T : L/8T = 1 : 1/8 = 8 : 1


  1. A man covers half of his journey at 6 km/h and the remaining half at 3 km/h. Find his average speed.









  1. View Hint View Answer Discuss in Forum

    Given, A = 6 km/h, B = 3 km/ h
    According to the formula, Average speed = 2AB/(A + B)

    Correct Option: B

    Given, A = 6 km/h, B = 3 km/ h
    According to the formula, Average speed = 2AB/(A + B)
    ∴ Required average speed = 2 x 6 x 3/(6 + 3)
    = 36/9 = 4 km/h



  1. A is twice as fast as B and B is thrice as fast as C. The journey covered by C in 56 min will be covered by A in ?









  1. View Hint View Answer Discuss in Forum

    Let time taken by A = Y
    Let speed of C = x
    Then, speed of B = 3x
    ∴ speed of A = 6x
    Now, ratio of speeds of A and C = Ratio of time taken by C and A
    6x : x = 56 : y

    Correct Option: D

    Let time taken by A = Y
    Let speed of C = x
    Then, speed of B = 3x
    ∴ speed of A = 6x
    Now, ratio of speeds of A and C = Ratio of time taken by C and A
    6x : x = 56 : y
    ⇒ 6x/x = 56/y
    ∴ y = 56/6 = 92/6
    = 91/3 min