A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together can do it in 2 hours. How long will B alone take to do it?
8 hours
10 hours
12 hours
24 hours
Explanation:
As 1 hours work =$ \dfrac{1}{4} $;
$\left(B + C\right)$s 1 hours work =$ \dfrac{1}{3} $;
$\left(A + C\right)$s 1 hours work =$ \dfrac{1}{2} $.
$\left(A + B + C\right)$s 1 hours work =$ \left(\dfrac{1}{4} +\dfrac{1}{3} \right) $=$ \dfrac{7}{12} $.
Bs 1 hours work =$ \left(\dfrac{7}{12} -\dfrac{1}{2} \right) $=$ \dfrac{1}{12} $.
B alone will take 12 hours to do the work.