Time and Work


  1. A can do a piece of work in 12 days. B is 60% more efficient than A. The number of days, it take B to do the same piece of work is ?









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    A's 1 day's work = 1/12
    B's 1 day's work = 1/12 + 60% of 1/12 = 1/12 x 160/100 = 2/15

    Correct Option: A

    A's 1 day's work = 1/12
    B's 1 day's work = 1/12 + 60% of 1/12 = 1/12 x 160/100 = 2/15

    ∴ B can do the work in 15/2 days = 71/2 days.


  1. A can finish a piece of work in 12 days while B can do it in 15 days. If both work at it together, what time will they take to do the work?









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    Efficiency of A = 100/12 = 8.33%
    Efficiency of B = 100/15 = 6.66%
    Combined efficiency of A and B = 8.33 + 6.66 = 15%

    Correct Option: C

    Efficiency of A = 100/12 = 8.33%
    Efficiency of B = 100/15 = 6.66%
    Combined efficiency of A and B = 8.33 + 6.66 = 15%
    Number of days taken by A and B, when worked together = 100/15
    = 62/3 days



  1. A can do a piece of work in 14 days while B can do it in 21 days. In how many days, working together they will complete the whole work?









  1. View Hint View Answer Discuss in Forum

    One day's work of A and B = 1/14 + 1/21 = 5/42

    Correct Option: C

    One day's work of A and B = 1/14 + 1/21 = 5/42
    ∴ Required number of days = 42/5 = 8.4 days


  1. A can do a piece of work in 24 days. If B is 60% more efficient than A, then the number of days required by B to do the same piece of work is ?









  1. View Hint View Answer Discuss in Forum

    Efficiency of A = 4.16%
    Efficiency of B = 1.6 x 4.16 = 6.66%

    Correct Option: B

    Efficiency of A = 4.16%
    Efficiency of B = 1.6 x 4.16 = 6.66%

    ∴ Number of days required by B = 100/6.66 = 15 days



  1. A is twice as good a workman as B and together they finish a piece of work in 14 days. In how many days can a alone finish the work?









  1. View Hint View Answer Discuss in Forum

    One day's work of A and B = 1/x + 1/2x = 1/14
    ∴ x = 21

    Correct Option: C

    One day's work of A and B = 1/x + 1/2x = 1/14
    ∴ x = 21
    Since A is twice efficient as B so A will take half of the day taken by B.