Time and Work


  1. Shashi can do a piece of work in 20 days. Tanya is 25% more efficient than Shashi. The number of days taken by Tanya to do the same piece of work is :









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    Time taken by Shashi in doing 1 work = 20 days
    Tanya is 25% more efficient than Shashi.
    ∴ Time taken by Tanya

    =
    100
    × 20 = 16 days
    125

    Correct Option: B

    Time taken by Shashi in doing 1 work = 20 days
    Tanya is 25% more efficient than Shashi.
    ∴ Time taken by Tanya

    =
    100
    × 20 = 16 days
    125


  1. If 10 people can do a job in 20 days, then 20 people with twice the efficiency can do the same job in









  1. View Hint View Answer Discuss in Forum

    In second case, the efficiency of a man is twice to that in the first case.
    ∴ M1D1 = 2 M2D2
    ⇒ 10 × 20 = 2 × 20 × D2

    ⇒ D2 =
    10 × 20
    = 5 days
    2 × 20

    Correct Option: A

    In second case, the efficiency of a man is twice to that in the first case.
    ∴ M1D1 = 2 M2D2
    ⇒ 10 × 20 = 2 × 20 × D2

    ⇒ D2 =
    10 × 20
    = 5 days
    2 × 20



  1. A works twice as fast as B. If B can complete a piece of work independently in 12 days, then what will be the number of days taken by A and B together to finish the work?









  1. View Hint View Answer Discuss in Forum

    A is twice efficient than B.
    ∴ Time taken by B = 12 days
    ⇒ Time taken by A = 6 days
    ∴ (A + B)’s 1 day’s work

    =
    1
    +
    1
    =
    2 + 1
    =
    1
    612124

    ∴ Required time = 4 days

    Correct Option: A

    A is twice efficient than B.
    ∴ Time taken by B = 12 days
    ⇒ Time taken by A = 6 days
    ∴ (A + B)’s 1 day’s work

    =
    1
    +
    1
    =
    2 + 1
    =
    1
    612124

    ∴ Required time = 4 days


  1. A man does double the work done by a boy in the same time. The number of days that 3 men and 4 boys will take to finish a work which can be done by 10 men in 8 days is









  1. View Hint View Answer Discuss in Forum

    According to the question,
    1 man ≡ 2 boys
    ∴ 3 men + 4 boys ≡ (3 + 2) men ≡ 5 men
    ∴ M1D1 = M2D2
    ⇒ 5 × D1 = 10 × 8

    ⇒ D1 =
    10 × 8
    = 16 days
    5

    Correct Option: B

    According to the question,
    1 man ≡ 2 boys
    ∴ 3 men + 4 boys ≡ (3 + 2) men ≡ 5 men
    ∴ M1D1 = M2D2
    ⇒ 5 × D1 = 10 × 8

    ⇒ D1 =
    10 × 8
    = 16 days
    5



  1. A is twice as good as B and together they finish a piece of work in 16 days. The number of days taken by A alone to finish the work is









  1. View Hint View Answer Discuss in Forum

    A is twice as good as B.
    ∴ Time taken by A = x days
    Time taken by B = 2x days
    According to the question,

    1
    +
    1
    =
    1
    x2x16

    2 + 1
    =
    1
    2x16

    3
    =
    1
    2x16

    ⇒ x = 3 × 8 = 24 days

    Correct Option: D

    A is twice as good as B.
    ∴ Time taken by A = x days
    Time taken by B = 2x days
    According to the question,

    1
    +
    1
    =
    1
    x2x16

    2 + 1
    =
    1
    2x16

    3
    =
    1
    2x16

    ⇒ x = 3 × 8 = 24 days