Taps lsquo A rsquo and lsquo B rsquo can fill a tank in 37 1 frasl 2 minutes and 45 minutes respecti...........

Quantitative Aptitiude (CLAT) Time and work

Taps ‘A’ and ‘B’ can fill a tank in 37 1⁄2 minutes and 45 minutes respectively. Both taps are opened and after some time tap ‘B’ is turned off. The tank is filled completely in exactly 30 minutes, if tap ‘B’ is turned off after:

9 minutes

10 minutes

15 minutes

12 minutes

Explanation:

Pipe A fills the tank in 75/2 Min.
As pipe A runs 30 mins it fills,
75/2 min = 1 tank
30 min = 1*2/75*30 = 4/5
Pipe A fills 4/5 in 30 mins, remaining 1/5
Pipe B fills 1 full tank in 45 mins,so
1 tank = 45 min
1/5 tank = 45/5 = 9 min