A cistern can be filled by a tap in 5 hours while it can be emptied by another tap in 8 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?	Pick:
A) 5.2 hrs
B) 13.3 hrs
C) 1.9 hrs
D) 7.2 hrs
E) 1.4 hrs

Rationale: "net part filled in 1 hour = ( 1 / 5 - 1 / 8 ) = 3 / 40 the cistern will be filled in 40 / 3 hrs i . e . , 13.3 hrs . answer : b"
Answer: B