Question

A cistern has 3 pipes A,B,C. A and B can fill it in 3 and 4 hours respectively, and C can empty it in 1 hour.if the pipes are opened at 3pm,4pm,5pm respectively on the same day,the cistern will be empty at:
A)7:12 pm
B)7:15 pm
C)7:10 pm
D)7:28 pm
Ans???​

Answer 1

Answer:

i think the cistern will be empty at 7:10 pm