1. 

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 33/7

III. If 10 men work for 3 days and thereafter 10 women replace them, the remaining work in completed in 4 days.
A. Any two of the three
B. I and II only
C. II and III only
D. I and III only
E. None of these

Answer: Option A

Explanation:

From I

(10 x 6) men can complete the work in 1 day.

⇒1 man's 1 day's work = 1/60

From II

(10 x 24/7) men + (10 x 24/7) women can complete the work in 1 day.

⇒ (240/7) men's 1 day work + (240/7) women's 1 day work = 1.

⇒ (240/7 x 1/60) + ( 240/7) women's 1 day's work = 1.

⇒ (240/7) women's 1 day's work = ( 1- 4/7) = 3/7

⇒ 10 women's 1 day's work = (3/7 x 7/240 x 10) = 1/8

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

From III

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

⇒ (10 x 3) men's 1 day's work + (10 x 4) women's 1 day's work = 1

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

Thus, I and III will give us the answer.

And, II and III will give us the answer.

∴ Correct answer is (A).