A takes twice as much time as B or thrice as much time as C to finish a piece of work. Working together, they can finish the work in 2 days. B can do the work alone in:
4 days
6 days
8 days
12 days
Explanation:
Suppose A, B and C take $ x $,$\dfrac{x}{2}$ and $\frac{x}{3}$ days respectively to finish the work.
Then,$ \left(\dfrac{1}{x} +\dfrac{2}{x} +\dfrac{3}{x} \right) $=$ \dfrac{1}{2} $
$\Rightarrow \dfrac{6}{x} $=$ \dfrac{1}{2} $
$\Rightarrow x $ = 12.
So, B takes $\left(12/2\right)$ = 6 days to finish the work.