Pipes and Cisterns Quiz Set 007


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Question 1

Three taps R, G and B are supplying red, green and blue colored inks into a tub. They can independently fill the tub in 3, 5 and 8 minutes. They are turned on at the same time. What is the ratio of blue ink after 3 minutes?

 A

${15/79}$.

 B

$1{8/39}$.

 C

${5/27}$.

 D

$3{1/9}$.

Soln.
Ans: a

Let the time taken by them to independently fill the tank be r, g and b minutes. Ink discharged by the blue tap is $3/b$. The total of all the inks is $3/r + 3/g + 3/b$. The ratio is ${1/b}/{1/r + 1/g + 1/b}$, which simplifies to ${rg}/{rg + gb + br}$ = ${15/79}$.


Question 2

Two pipes can together fill a cistern in 8 minutes. How long does the slower alone take if the speeds of the pipes are in the ratio 4 : 1?

 A

40 mins.

 B

41 mins.

 C

39 mins.

 D

42 mins.

Soln.
Ans: a

Let the time taken by the slower pipe alone be x. Then 8 × $(1/x + 4/x)$ = 1. Solving for x, we get x = 8 × 5 = 40 mins.


Question 3

Tap X can fill the tank in 16 mins. Tap Y can empty it in 12 mins. In how many minutes will the tank be emptied if both the taps are opened together when the tank is $9/18$th full of water?

 A

24 mins.

 B

25 mins.

 C

23 mins.

 D

9 mins.

Soln.
Ans: a

1 filled tank can be emptied in ${16 × 12}/{16 - 12}$ mins. So 9/18 can be emptied in ${16 × 12}/{16 - 12}$ × $9/18$ = 24 mins.


Question 4

Three taps R, G and B are supplying red, green and blue colored inks into a tub. They can independently fill the tub in 8, 8 and 5 minutes. They are turned on at the same time. What is the ratio of blue ink after 3 minutes?

 A

${4/9}$.

 B

$1{5/8}$.

 C

${4/11}$.

 D

$2{9/11}$.

Soln.
Ans: a

Let the time taken by them to independently fill the tank be r, g and b minutes. Ink discharged by the blue tap is $3/b$. The total of all the inks is $3/r + 3/g + 3/b$. The ratio is ${1/b}/{1/r + 1/g + 1/b}$, which simplifies to ${rg}/{rg + gb + br}$ = ${4/9}$.


Question 5

Tap M can fill a cistern in 14 mins. And, a tap N can empty it in 12 mins. In how many minutes will the cistern be emptied if both the taps are opened together when the tank is $5/19$th already empty?

 A

$61{17/19}$ mins.

 B

$66{7/18}$ mins.

 C

$55{2/21}$ mins.

 D

$58{5/7}$ mins.

Soln.
Ans: a

1 filled cistern can be emptied in ${14 × 12}/{14 - 12}$ mins. So $1 - 5/19$ = $14/19$ filled cistern can be emptied in ${14 × 12}/{14 - 12}$ × $14/19$ = ${1176/19}$, which is same as: $61{17/19}$ mins.


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Updated on 2020-02-07. Published on: 2016-05-05

Posted by Parveen(Hoven),
Aptitude Trainer


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