Question

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

• A. $24$ days
• B. $27$ days
• C. $36$ days
• D. $48$ days

Answer 1

The correct option is C $36$ days

Let us consider work done by $B$ in $1$ day $=x$

So, the work done by $A$ in $1$ day $=2x$

Now,

Number of days $A$ and $B$ together requires to complete a piece of work $=12$ days

Work done by both $A$ and $B$ together in $1$ day $=1/12$

$\therefore 2x+x=1/12$
$3x=1/12$

$x=1/36$

$\therefore B$ can do work in $36$ days