48
Q:

# 8 litres are drawn from a cask full of wine and is then filled with water. This operation is performed three more times. The ratio of the quantity of wine now left in cask to that of the water is 16 : 65. How much wine the cask hold originally?

 A) 18 litres B) 24 litres C) 32 litres D) 42 litres

Answer:   B) 24 litres

Explanation:

Let the quantity of the wine in the cask originally be x litres
Then, quantity of wine left in cask after 4 operations =$\inline \fn_cm \left [ x(1-\frac{8}{x})^4 \right ]$litres

$\inline \fn_cm \therefore \left [ \frac{x(1-\frac{8}{x})^4}{x} \right ]=\frac{16}{81}$

$\inline \fn_cm \Rightarrow \left [ 1-\frac{8}{x} \right ]^4=(\frac{2}{3})^4$

$\inline \fn_cm \Rightarrow \left ( \frac{x-8}{x} \right )=\frac{2}{3}$

${\color{Black}&space;\Rightarrow&space;3x-24=2x}$

${\color{Black}&space;\Rightarrow&space;x=24}$

Q:

640 ml of a mixture contains milk and water in ratio 6:2. How much of the water is to be added to get a new mixture containing half milk and half water ?

 A) 360 ml B) 320 ml C) 310 ml D) 330 ml

Answer & Explanation Answer: B) 320 ml

Explanation:

Here total parts of milk and water in the solution is 6+2 = 8 parts
1part = 640/8 = 80
old mixture contains 6parts of milk and 2 parts of water(6:2).
To get new mixture containing half milk and half water, add 4parts of water to the old mixture then 6:(2+4) to make the ratio same.
i.e, 4 x 80 = 320 ml.

4 114
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

2 123
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%

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%.

5 93
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,
$\inline \fn_jvn \small \frac{4.5}{4.5+x}=\frac{3}{7}$
=> x=6
Hence 6ml of water is added.

3 163
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%