Question

A and B together can complete a work in 3
days. They start together. But, after 2 days,
B left the work. If the work is completed after
2 more days, B alone could do the work in
(S.S.C. 2007)​

Answer 1

Answer:

6 days

Step-by-step explanation:

(A+B)'s one day's work = 13

part

(A+B) works 2 days together = 23

part

Remaining work = 1−23

 = 13

part

13

part of work is completed by A in two days

Hence, one day's work of A = 16

Then, one day's work of B = 13−16

 = 16

So, B alone can complete the whole work in 6 days.

Answer 2

Answer:

6 days

Step-by-step explanation:

6 days

Let the total unit of work be 6 units (LCM of 2 and 3)

(A+B)do=36=2 units/day

(A+B)′s2 day work =2×2=4 units

Work left =6−4=2 units

This remaining work is done by A in 2 days.

∴A′s per day work =22=1 unit/day

∴B′s per unit work =(A+B)′s work−A′s work

=2−1=1 unit/day

B alone can complete the work in =16=6 days.