Mark and John can do a piece of work in 20 days and 30 days, respectively . Find their work done together in one day.
Answers
Step-by-step explanation:
Part of work done by A in 1 day=
10
1
Part of work done by B in 1 day=
20
1
∵B alone worked during last 4 days.
∴ part of work done by B in 4 days=
20
4
=
5
1
part of work done by A and B(before 4 days of complete work) =1−
5
1
=
5
5−1
=
5
4
part of work done by A and B in 1 day=
10
1
+
20
1
=
20
2+1
=
20
3
20
3
part of work done by A and B in 1 day.
1 part of work done by A and B in
20
3
1
day =
3
20
days.
∴
5
4
part of work is done by A and B in
3
20
×
5
4
days
=
3
16
days
5
3
1
days.
Mary M and John J can finish a piece of work = 24 days
(M+J)'s 1 day job = 1/24
John J and Vino V can finish the same amount of work = 30 days
(J+V)'s 1 day job = 1/30
Vino V and Mary M can finish the same piece of work = 40 days
(V+M)'s 1 day job = 1/40
Now
(M+J+V)'s 1 day job = 1/24 + 1/30 + 1/40
2(M+J+V) = (5+4+3)/120
2(M+J+V) = 12/120
2(M+J+V) = 1/10
(M+J+V) = 1/20
They altogether can finish the work in 20 days.