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 5 of 21.

Manoj said:   9 years ago
water : syrup=3:5
requeired 1:1
3:5::a:b=1;1
3b=1
5a=1
a=1/5.
(1)

Himanshu321_hani said:   8 years ago
The Formula is /2*[Big value -small value/ Big value].
(1)

Mir said:   7 years ago
When a mixture is drawn, both syrup and water is drawn equally.

So, if 1 part from water and 1 part of syrup(total 2 parts) is drawn, the ratio of 3:5 becomes 2:4. When replaced wit 2 parts of water, gives the ratio 4:4 i..e 1:1.

Therefore mixture drawn is 2/8 or 1/4.
(1)

Tinku said:   6 years ago
Can anyone tell me, how to find a total mixture here?
(1)

Twinkle said:   6 years ago
Simply;

(3/8) - (3x/8) + x = (4/8);
This will give x = 1/5.
(1)

Som said:   4 years ago
It is not Volume of vessel.

It's a Volume of mixture at initial.
(1)

Ankush said:   2 months ago
3Lwater + 5L syrup = 8L mix.
Now 1 unit of mix will also have 3 parts water and 5 parts syrup,
Let 1 unit be 800 ml for easy calculation.
And in 800ml we have 300ml water + 500ml syrup
Now, remove 1 unit from the total, you will have a mix of 7.2L.
removed 1unit = 800ml in 7.2L × 5/8 = 4.5 L syrup left.
And add 800ml of water in its place.
New ratio of mix 4.5l syrup: 2.7 old +0.8 newly added
4.5:3.5 we need 4:4 for both equal
Remove 1 more unit from the mix.
7.2 - 0.8 = 6.4L.
Syrup left 6.4L × 5/8 = 4.0L
Add water in place of 800ml
Now you have 4L syrup: 4L water.

Replacement of syrup with water = 800ml × 2 = 1.6L.

Now, how much replacement from the original 8L in ratio?
So, 1.6/8 total replacement reduces to 1/5(ans).
(1)

Sandhya said:   2 decades ago
Can you give a shortcut for this?

Murali said:   2 decades ago
I did not get last Step. Could you please explain how it was?

So, part of the mixture replaced =

(8/5) * (1/8) =1/5.

Madhu said:   2 decades ago
Excellent Kiran! Your answer is very nice.


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