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Q:

In a mixture of milk and water, there is only 26% water. After replacing the mixture with 7 liters of pure milk , the percentage of milk in the mixture  become 76%. The quantity of mixture is:

A) 65 liters B) 91 liters
C) 38 liters D) None of these

Answer:   B) 91 liters

Explanation:

         Milk             Water

         74%             26%        (initially)

         76%             24%        ( after replacement)

        Left amount = Initial amount \left ( 1-\frac{replaced\: amount}{total \: amount} \right )

                     24  = 26\left ( 1-\frac{7}{k} \right )

                  \Rightarrow \: \: \frac{12}{13}=\left ( 1-\frac{7}{k} \right )

                  \Rightarrow \: \: \frac{1}{13}=\frac{7}{K}

                  \Rightarrow \: \: K=91l

Q:

Equal quantities of three mixtures of milk and water are mixed in the ratio 1:2, 2:3 and 3:4. The ratio of water and milk in the mixture is ?

A) 193 : 122 B) 97 : 102
C) 115 : 201 D) 147 : 185
 
Answer & Explanation Answer: A) 193 : 122

Explanation:

Given the three mixtures ratio as (1:2),(2:3),(3:4)

(1+2),(2+3),(3+4)

Total content = 3,5,7

Given equal quantities of the three mixtures are mixed, then LCM of 3, 5, 7 = 105

105/3 = 35 , 105/5 = 21 , 105/7 = 15

Now, the individual equal quantity ratios are (35x1, 35x2), (21x2, 21x3), (15x3, 15x4)

(35,70), (42,63), (45,60)

So overall mixture ratio of milk and water is

35+42+45 : 70+63+60

122:193

But in the question asked the ratio of water to milk = 193 : 122

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1 32
Q:

In a mixture of milk and water the proportion of water by weight was 75%. If in 60 gm of mixture 15 gm water was added, what would be the percentage of water ? (Weight in gm)

A) 80% B) 70%
C) 75% D) 62%
 
Answer & Explanation Answer: A) 80%

Explanation:

Water in 60 gm mixture=60 x 75/100 = 45 gm. and Milk = 15 gm.

After adding 15 gm. of water in mixture, total water = 45 + 15 = 60 gm and

weight of a mixture = 60 + 15 = 75 gm.

So % of water = 100 x 60/75 = 80%.

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3 32
Q:

The amount of water (in ml) that should be added to reduce 9 ml lotion, containing 50% alcohol, to a lotion containing 30% alcohol is ?

A) 6 ml B) 11 ml
C) 15 ml D) 9 ml
 
Answer & Explanation Answer: A) 6 ml

Explanation:

Let us assume that the lotion has 50% alcohol and 50% water.
ratio = 1:1
As the total solution is 9ml
alcohol = water = 4.5ml
Now if we want the quantity of alcohol = 30%
The quantity of water = 70%
The new ratio = 3:7
Let x ml of water be added
We get,

=> x=6
Hence 6ml of water is added.

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3 28
Q:

If a man buys 1 lt of milk for Rs.12 and mixes it with 20% water and sells it for Rs.15, then what is the percentage of gain ?

A) 25% B) 30%
C) 17% D) 19%
 
Answer & Explanation Answer: A) 25%

Explanation:

He has gain = 15 - 12 = 3,
Gain% = (3/12) x 100 = (100/4) = 25.
He has 25% gain.

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4 40
Q:

One type of liquid contains 25 % of benzene, the other contains 30% of benzene. A can is filled with 6 parts of the first liquid and 4 parts of the second liquid. Find the percentage of benzene in the new mixture.

A) 27 % B) 26 %
C) 29 % D) 21 %
 
Answer & Explanation Answer: A) 27 %

Explanation:

Let the percentage of benzene = X
(30 - X)/(X- 25) = 6/4 = 3/2
=> 5X = 135  
X = 27

So, required percentage of benzene = 27 %

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