Q.1 There are three inlets P,Q & R attached with a tank. If P & Q are opened then tank is filled in 120hr & if P & Q are opened then tank is filled in 90 hr. Find the time in which P,Q & R can fill the tank, if these all are opened ? A) 60 h B) 61 h C) 62 h D) 63 h Ans. A Shortcut : 2xyz / xy + yz + zx 2*72*120*90 / 25920 = 60 h Q.2 Because of a hole in a bottom of a tank , a tank becomes empty in 6 min. after opening a tap which fills the tank at the rate of 8 lit/min the tank is emptied in 10 min. Find the capacity of the tank ? A) 117 litre B) 118 litre C) 119 litre D) 120 litre Ans. D Shortcut : abc / c-a i.e. 6*8*10 / 10-6 = 120 litre Q.3 Two pipes can separately fill a tank in 10 hr & 15 hr. Both the pipes are opened to fill the cistern but when the tank is 1/3rd full a leak develops in the tank through which 1/3rd of water supplied but both the pipes leak out . What is the total time taken to fill the tank ? A) 6 hr. B) 10 hr. C) 12 hr. D) 15 hr. Ans. A Time taken by the two pipes to fill the tank: 10*15/10+15 =6 hr. Q.4 A pipe can fill a bath in 20 minutes and another can fill it in 30 minutes. A person opens both the pipes simultaneously. When the bath should have been full, he finds that the waste pipe was open. He then closes the waste pipe and in 3 more minutes the bath is full. In how much time would the waste pipe empty it? A) 50 min B) 48 min C) 44 min D) 38 min Ans. B First pipe can fill the cistern = 20 min Second pipe fill the cistern = 30 min. But together both pipes can fill it = = 12 min Now according to question 12 = 1 {Where x = Time taken by leak to empty the cistern} 1 – = 1 x = 48 min Q.5 A supply of water lasts for 15 days if 12 gallons leak off everyday, but only for 100 days if 15 gallons leak off daily . What is the total quantity of water in the supply ? A) 900 B) 1125 C) 3350 D) 1250 Ans. A consumption be x and supply y: 150x + 12*150 = y ....(i) 100x + 15*100 = y ....(ii) multiply i by 2 and ii by 3 and equate, 4500 - 3600 = 3y - 2y y = 900