Tick (✓) the correct answer:
3 men or 5 women can do a work in 12 days. How long will 6 men and 5 women take to do it?
(a) 6 days
(b) 5 days
(c) 4 days
(d) 3 days
(c) 4 days
Three men can complete the work in 12 days.
Thus, one man can complete the work in 36 days.
Rate of work done by one man in 1 day $=\frac{1}{36}$
Similarly, rate of work done by one woman in 1 day $=\frac{1}{5 \times 12}=\frac{1}{60}$
Now, six men will do $\frac{6}{36}$, i.e., $\frac{1}{6}$ unit of work in a day.
Five women will do $\frac{5}{60}, \mathrm{i}, \mathrm{e} ., \frac{1}{12} \mathrm{unit}$ of work in a day.
$\therefore$ Total work done in 1 day $=\frac{1}{6}+\frac{1}{12}=\frac{1}{4}$ unit
Thus, six men and five women will take 4 days to complete the work.
The work can be completed in 4 days.