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10 litres are removed from 80 litres of solution of milk and water hav

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Math Expert
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V
Joined: 02 Sep 2009
Posts: 65187
10 litres are removed from 80 litres of solution of milk and water hav  [#permalink]

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New post 11 Jan 2020, 05:59
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10 litres are removed from 80 litres of solution of milk and water having ratio of milk and water as 4 : 3 and replaced with water. This operation is done a total of three times. What is the ratio of milk and water in the solution now ?


A. 47/128
B. 48/128
C. 49/128
D. 50/128
E. 51/128

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Joined: 02 Sep 2009
Posts: 65187
Re: 10 litres are removed from 80 litres of solution of milk and water hav  [#permalink]

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New post 11 Jan 2020, 06:00
Intern
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B
Joined: 01 Aug 2018
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Re: 10 litres are removed from 80 litres of solution of milk and water hav  [#permalink]

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New post 02 Jun 2020, 22:38
Can somebody please solve this ? I am not able to crack this question. Thanks.
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G
Joined: 09 Nov 2015
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Re: 10 litres are removed from 80 litres of solution of milk and water hav  [#permalink]

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New post 06 Jun 2020, 23:47
1
I have checked and rechecked but I am getting 49/79 as the ratio of Milk:Water in the resultant solution.

Initial qty of milk in the 80 L solution is (80/7)*4=320/7. Qty of milk remaining after 10 L of solution is removed and replaced with 10 L of water three times is (320/7)*(7/8)^3=(5*49)/8. Since the qty of solution remains unchanged, the qty of water becomes 80-(5*49)/8. Therefore, the ratio of Milk to Water in the final solution is 49/79. IMO, had the question asked for the FRACTION of Milk in the final solution then the answer would be 49/(79+49)=49/128.
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Re: 10 litres are removed from 80 litres of solution of milk and water hav  [#permalink]

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New post 07 Jun 2020, 08:22
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1
2
Final qty of milk =
4/7×(1-10/80)^3
= 49/128
Final ratio of milk and water
= 49/79
Final qty=
initial qty(1- qty repl/tot qty)^number of times repl

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Intern
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10 litres are removed from 80 litres of solution of milk and water hav  [#permalink]

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New post 22 Jun 2020, 21:35
Hi,

Can someone please confirm this.
The question asks for ratio of milk to water which is 49:79
ratio of milk to solution = 49:128
(this is also confirmed in the twin question as mentioned by Bunnel above which asks quantity of milk in final solution = 49/128 * 80 = 245/8 L)
ratio of water to solution = 79 : 128

Similar question:
https://gmatclub.com/forum/12-5-of-a-so ... 89617.html
GMAT Club Bot
10 litres are removed from 80 litres of solution of milk and water hav   [#permalink] 22 Jun 2020, 21:35

10 litres are removed from 80 litres of solution of milk and water hav

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