Aptitude - Alligation or Mixture - Discussion

Discussion Forum : Alligation or Mixture - General Questions (Q.No. 1)
1.
A vessel is filled with liquid, 3 parts of which are water and 5 parts syrup. How much of the mixture must be drawn off and replaced with water so that the mixture may be half water and half syrup?
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Answer: Option
Explanation:

Suppose the vessel initially contains 8 litres of liquid.

Let x litres of this liquid be replaced with water.

Quantity of water in new mixture = 3 - 3x + x litres
8

Quantity of syrup in new mixture = 5 - 5x litres
8

3 - 3x + x = 5 - 5x
8 8

5x + 24 = 40 - 5x

10x = 16

x = 8 .
5

So, part of the mixture replaced = 8 x 1 = 1 .
5 8 5

Discussion:
201 comments Page 2 of 21.

Bikram Tisso said:   3 years ago
Anyone, Please explain in the simplest way to understand.
(19)

Sukumar Natarajan said:   4 years ago
Consider: water is 30 lr and Syrup is 50 lr.

We have to take out 10lr syrup from 50lr. it is clearly 20%.

Note:
It means we are taking out 20 % (= 10 lr) syrup and 20 % (= 6lr) water.
Now we have 40-liter syrup and 24-liter of water remaining. Then we are adding 16-liter water.
Now we have 40-liter syrup and 40-liter water.
(17)

Priyanshu Chaudhary said:   2 years ago
If we remove 1 amt of the mixture -> 5/8 amt of syrup is removed.
Let's say our ans is x -> remove x amt of mixture -> (5/8)x or syrup is removed.
for both water and syrup to be in the same amount, the syrup should be 4/8 that is 1/8 of the syrup should be removed from the mixture.
Therefore (5/8)x = 1/8 => x = 1/5 =>ANSWER.
(17)

Radhakrishnan said:   5 years ago
Hey, their is a simple way.
Using the left value rule
Left value= intial value * (1- fraction replaced)
We need to find fraction replaced,
Left v = 1/2.
Initial value = 5/8.

Therefore;
1/2 = 5/8 * (1-f).
4/5 = 1-f.
f = 1/5.
(10)

Atr said:   3 years ago
I didn't get this clearly. Please anyone help me.
(10)

Sriman said:   6 years ago
Can anyone please explain how 8/5X1/8 come? Please explain.
(8)

ADITYA PANDITA said:   8 years ago
@All.

The reason in the last step 8/5 is multiplied with 1/8 (or you could say 8/5 is divided by 8) is because we have found x in liters and the answer is required in parts. The 8 that we have used to divide in the last step is not the total 8 parts but it is the 8 liters we have assumed in the beginning of the answer.
(7)

Pujitha said:   2 years ago
@Kamakshi Puri.

The question is about not removing syrup but removing a mixture of the same quantity. So, the water should be added.
(7)

Mrityunjay Yadav said:   6 months ago
At last, we have to find 8/5 litre is how many litres of 8 litres.
So it is 8/5 divide by 8 = 8/5 * 1/8.
(6)

SurendraReddy said:   2 decades ago
NOTE: Liquid = Mixed substance (water,syrup)
Let the volume of the vessel = x liters.
Out of this x liters 3/8(x) is water & 5/8(x) is syrup.
Let y liters of liquid is taken out. So out of this y liters 3/8(y) is water and 5/8(y) is syrup.
The water in the remaining liquid is 3/8(x-y) .
The syrup in the remaining liquid is 5/8(x-y).
Now y liters of water is added to the remaining liquid so that the final liquid contains half water and half syrup.
=> 3/8(x-y)+y=5/8(x-y)
=>y=1/5(x)
or y = 1/5(x).
Answer: The amount of liquid drawn out = The amount of water added = 1/5 of x.
(4)


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