A alone can do a work in 20 days. A is 20% less efficient than B. In how many days can B alone do the work?
1). 12
2). 18
3). 16
4). 24
Let, B alone can do the work in = x days
Let, efficiency of B = y
∴ efficiency of A = y - y × 20/100 = 0.8y
According to problem,
⇒ x × y = 20 × 0.8y
⇒ x = 16
∴ B alone can do the work = 16 days