If m men can do a job in d days, then the number of days in which m+r men can do the job is

(A) d+r; (B) \( \frac{d}{m} (m+r)\) ; (C) \( \dfrac {d}{m+r} \) ; (D) \( \dfrac {md}{m+r} \);

**Discussion:**

If m men can do a job in d days,

Then m men does \( \frac {1}{d} \) job in 1 day

Then 1 man does \( \frac {1}{md} \) job in 1 day

Then m+r men does \( \frac {m+r}{md} \) job in 1 day

Then m+r men does 1 job \( \frac {md}{m+r} \) days.

Hence answer is \( \dfrac {md}{m+r} \) days (D)

## Chatuspathi:

**What is this topic:**Arithmetic**What are some of the associated concepts:**Unitary Method**Where can learn these topics:**Cheenta I.S.I. & C.M.I. course, discusses these topics in the ‘Arithmetic’ module.**Book Suggestions:**Arithmetic by K.C. Nag

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