The maximum total work done for three consecutive days will be when A, B and C work in distinct pairs (for example ‘A and B’, ‘B and C’ and 'C and A’). Hence on these three days fraction of total work done will be: 2(
1
8
+
1
12
+
1
30
)−
58
120
Maximum possible work done in the first 6 days 2(
1
8
+
1
12
+
1
30
)=2(
58
120
)=
116
120
The remaining
4
120
fraction of work can be done in least amount of time if A and B work together on the 7th day. A and B together can do
1
8
+
1
12
=
5
24
fraction ofwork in a day. So, they will complete the