SSC Selection Post 2022 PYQ — Question 61

The correct answer is option 2 i.e. 54.

Efficiency ratio of A : B = 2 : 1

Time ratio (since time ∝ 1/efficiency) = 1 : 2

Let A can complete the work in x days,

Then B will complete it in 2x days

A's 1 day work = 1/x

B's 1 day work = 1/2x

Together = $\frac{1}{x} + \frac{1}{2x} = \frac{1}{18}$​

$\frac{2 + 1}{2x} = \frac{3}{2x} \Rightarrow \frac{3}{2x} = \frac{1}{18} \Rightarrow 2x = 3 \times 18 = 54$