A is 1.5 times as efficient as B. A & B together complete the work in 12 days. In how many days, A alone can complete the work?

20 days

Given,

A : B = 3 : 2 (Efficiency)

⇒ A + B can complete a work in 12 days = (3 + 2) x 12 = 5 x 12 = 60 units,  ..(Efficiency × Days = Total work)

⇒ Time required by A to complete the work alone = \(\frac{60}{3}\) = 20 days,   ..(\(\frac{Work}{Efficiency}\) = Time)