Madhya Pradesh Police Exam Model Paper 8

Given:
A and B together can complete a particular task in 4 days.
And A alone can complete the same task in 6 days.
Calculation:
According to the question:
Work done by (A + B) in 4 days
⇒ Work done by (A + B) in 1 days = 1/4
Again,
Work done by A alone in 6 days.
⇒ Work done by A alone in 1 days $=1/6$
Work done by B alone in 1 days $=\left(1/4\right)\mathit{–}\left(1/6\right)$
$\Rightarrow \left(3\mathit{–}2\right)/12$
$\Rightarrow 1/12$
∴ The total time taken by B to complete the work is 12 days.
A + B = 4 days
A = 6 days
L..C.M (4 , 6) = 12
⇒ A + B = 4 days
(A + B) efficiency $=12/4=3$
⇒ A = 6 days
A efficiency $=12/6=2$
So B efficiency $=3-2=1$
$\Rightarrow \mathit{B}=12/1=12$ days
∴ The total time taken by B to complete the work is 12 days.