UP Police Constable Exam Model Paper 3

Given:
A and B together can complete a work = 18 days
Calculations:
Let the efficiency of B be '1x' unit
The efficiency of A = 2x units
A and B together can complete in one day = 3x units
They worked together for 1 day they can complete = 1/18
⇒ x + 2x = 1/8
⇒ 3x = 1/18
⇒ x = (1/18) × 1/3
⇒ x = 1/54
B can complete 1/54${}^{\mathrm{th}}$ work completed in one day, Hence B alone can finish the work in 54 days.
A alone can finish = B/2 days
⇒ 54/2 = 27 days
∴ A alone can finish work in 27 days