A works twice as fast as B. If both of them together can finish a piece of work in 12 days, then B alone can do it in:

Correct option is C

Given:

A work twice as fast as B

Work done when both A and B work together = 12 days

Formula Used:

Work done = Efficiency of each worker$$\times$$​ Time

Solution:

Let B’s efficiency be 1

Then A’s efficiency is twice of B = 2

Total efficiency of both A and B working together = 1 + 2 = 3

Total work = Efficiency $$\times$$ Time $$=3\times 12 =36 \, units$$​​

B alone can do the work = $$\frac{Total\ Work}{Efficiency}= \frac{36}{1} = 36 days$$​​