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    A can do a work in 13 days and B can do the same work in 24 days. If they work on it together for 5 days, then what fraction of the work is left?
    Question

    A can do a work in 13 days and B can do the same work in 24 days. If they work on it together for 5 days, then what fraction of the work is left?

    A.

    129/312

    B.

    127/312

    C.

    133/312

    D.

    137/312

    Correct option is B

    Given:

    A can finish the work in 13 days

    B can finish the work in 24 days

    They work together for 5 days

    Find the fraction of work left

    Formula Used: 

    Total work = Rate × time

    Solution:

    Total work = LCM( 13, 24) = 312 units

    A’s 1-day work = 31213 \frac{312}{13} = 24 units

    B’s 1-day work = 31224\frac{312}{24}​ = 13 units

    Work done in 5 days by A and B:

    = ( 24 + 13) × 5 

    = 37 × 5 = 185 units

    Remaining Work = 312 - 185 = 127 units

    Fraction of work left 127312\frac{127}{312}

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