two pipes A and B can fill a tank in 15 hours and 20 hrs respectively while a 3rd pipe C can empty the full tank in 25 hrs. all the three pipes are opened in the beginning .after 10 hrs , C is closed . in how much time will the tank be full.
Answers
Answered by
1
The Tank will be full after 2 hrs
Answered by
2
Answer:
Correct option is
A
12 hours
Part of the tank filled when all the three pipes are opened for 10 hours
=10×(
15
1
+
20
1
−
25
1
)=10×(
300
20+15−12
)=
300
230
=
30
23
Remaining empty part = 1−
30
23
=
30
7
Part of the tank filled in 1 hour by pipes (A and B) =
15
1
+
20
1
=
60
4+3
=
60
7
∵
60
7
part is filled in 1 hour
30
7
part is filled in 2 hours
∴ Total time to fill the tank =10+2=12 hours
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