A barrel full of beer has 2 taps one midway,,which draw a litre in 6 minutes and the other at the bottom,which draws a litre in 4 minutes. The lower tap is lower normally used after the level of beer in the barrel is lower than midway.The capacity of the barrel is 36 litres. A new assistant opens the lower tap when the barrel is full and draws out some beer. As a result the lower tap has been used 24 minutes before the usual time. For how long was the beer drawn out by the new assistant ?  Choose the correct choice from the following choices:
A) 15 minutes	B) 16 minutes	C) 17 minutes	D) 18 minutes	E) None of these
Sol. The top tab is operational till 18 litres is drawn out.   ∴ Time after which the lower tap is usually open   = 18 × 6 = 108 minutes   ∴ Time after which it is open now = 108 – 24 = 84 minutes   ∴ Litres drawn = 84/6= 
<gadget id="calculator">84/6</gadget>
<output>14</output>
14 litres   ∴ 18 – 14= 4 litres were drawn by the new assistant.   ∴ Time = 4 × 4 = 16 minutes Answer 16 minutes
<result>B</result>
A barrel full of beer has 2 taps one midway,,which draw a litre in 6 minutes and the other at the bottom,which draws a litre in 4 minutes. The lower tap is lower normally used after the level of beer in the barrel is lower than midway.The capacity of the barrel is 36 litres. A new assistant opens the lower tap when the barrel is full and draws out some beer. As a result the lower tap has been used 24 minutes before the usual time. For how long was the beer drawn out by the new assistant ?