Time and Work


  1. A man, on tour travel first 160 km, at 64 km/hr. and the next 160km at 80km/hr. the average speed for the first 320 km. of the tour is ?









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    Average speed = 2t1 x t2/( t1 + t2)

    Correct Option: B

    Average speed = 2t1 x t2/( t1 + t2)
    = (2x64x80)/(64+80)km
    = (2 x 64 x 80 ) / 144 km/hr.
    =71.11km/hr.


  1. By walking at 3/4 of his usual speed, a man reaches his office 20 minute later than usual. this usual time is ?









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    At a speed of 3/4 of the usual speed, the time taken is 4/3 of the usual time

    Correct Option: B

    At a speed of 3/4 of the usual speed, the time taken is 4/3 of the usual time
    = (4/3 of usual time ) – (usual time ) = 20min.
    ⇒ 4x/3 -x = 20
    ⇒ x/3 =20
    ⇒ x=60 min



  1. A man travels 35 km partly at 4 km/hr and at 5 km/hr. If he covers former distance at 5 km/hr and later distance at 4 km/hr, he could cover 2 km more in the same time. The time taken to cover the whole distance at original rate is









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    Suppose the man covers first distance in x hrs. and second distance in y hrs.

    Correct Option: D

    Suppose the man covers first distance in x hrs. and second distance in y hrs.
    Then , 4x + 5y = 35 and 5x +4y= 37
    Solving these equation , we get
    X=5 and y=3
    Total time taken = (5+3) hrs= 8hrs


  1. 6 men or 10 women can reap a field in 15 days, then the number of days that 12 men and 5 women will take to reap the same field is :









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    Work done by 6 men = work done by 10 women.
    Work done by 1 man = work done by 10 / 6 = 5/3 women
    ∴ 12 men + 5 women = 12 x ( 5 / 3) + 5 = 25 women
    ∴ W1 x D 1 = W2 x

    Correct Option: B

    Work done by 6 men = work done by 10 women.
    Work done by 1 man = work done by 10 / 6 = 5/3 women
    ∴ 12 men + 5 women = 12 x ( 5 / 3) + 5 = 25 women
    ∴ W1 x D 1 = W2 x D2 W = women, D=days
    10 X 15 = 25 x D2
    D2 = 6



  1. 6 children and 2 men complete a certain piece of work in 6 days. Each child takes twice the time taken by a man to finish the work. In how many days will 5 men finish the same work?









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    6C + 2M = 6days
    36C + 12M = 1 days
    Again 1M = 2C
    ∴ 36+12X2 = 1 day
    60 children can do the work in 1 day

    Correct Option: A

    6C + 2M = 6days
    36C + 12M = 1 days
    Again 1M = 2C
    ∴ 36+12X2 = 1 day
    60 children can do the work in 1 day
    Now, 5 men = 10 children
    ∴ 10 children can do the work in 6 days.