Taps A and B can fill a bucket in 12 minutes and 15 minutes respectively. If both are opened and B is closed after 3 minutes, how much further time would it take for A to fill the bucket? Choose the most appropriate option.
A) 5min. 50sec.
B) 5min. 30 sec.
C) 6 min 36 sec.
D) 6mins. 32 sec.
E) 6 min. 15 sec.
Explanation:   Part filled in 3 minutes =   3∗(1/12+1/15)=3∗9/60=9/20   Remaining part =1−9/20=11/20   =&gt;1/12:11/20=1:X   =&gt;X=6.6 mins.   =&gt;X=6.6 mins.   So it will take further 6 mins 36 seconds to fill the bucket.   Option 6 min 36 sec.
<result>C</result>
Taps A and B can fill a bucket in 12 minutes and 15 minutes respectively. If both are opened and B is closed after 3 minutes, how much further time would it take for A to fill the bucket?