A cistern can be filled by a tap in 3 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 one:  A) 4.8 hr  B) 2.4 hr  C) 3.6 hr  D) 1.8 hr  E) 2.0 hr
Explanation:   Part filled by one tap in 1 hour =1/4   Part emptied by second tap 1 hour =1/8   Net part filled by both these taps in 1 hour   =1/3-1/8=5/24   i.e, the cistern gets filled in  24/5= 
<gadget id="calculator"> 24/5</gadget>
<output>24/5 = around 4.8</output>
4.8 hrs   4.8 hrnswer: Option 4.8 hr
<result>A</result>
A cistern can be filled by a tap in 3 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?