In how many days can 10 women finish a work ?
I. 10 men can complete the work in 6 days.
II. 10 men and 10 women together can complete the work In 3 3/7 days.
III. If 10 men work for 3 days and there after 10 women replace them, the remaining work is completed in 4 days.

I : 10 men complete work in 6 days

=> 1 man 1 day's work = $$\frac{1}{60}$$

II : $$(10 \times \frac{24}{7})$$ men + $$(10 \times \frac{24}{7})$$ women = 1 day

=> $$(\frac{240}{7})$$ men's 1 day's work + $$(\frac{240}{7})$$ women's 1 day's work = 1

=> $$(\frac{240}{7} \times \frac{1}{60})$$+ $$(\frac{240}{7})$$ women's 1 day's work = 1

=> $$(\frac{240}{7})$$ women's 1 day's work = $$1 - \frac{4}{7} = \frac{3}{7}$$

=> 10 women's 1 day's work = $$\frac{3}{7} \times \frac{7}{240} \times 10 = \frac{1}{8}$$

So, 10 women can finish the work in 8 days.

III : (10 men's work for 3 days) + (10 women's work for 4 days) = 1

=> 30 men's 1 day's work + 40 women's 1 day's work  = 1

Again, repeating the same procedure, we can find out the time taken by 10 women to finish the work.

Thus, any 2 of the three statements is sufficient.