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