12
Q:

4 kg of a metal contains 1/5 copper and rest in Zinc. Another 5 kg of metal contains 1/6 copper and rest in Zinc.The ratio of Copper and Zinc  into the mixture of these two metals:

 A) 49 : 221 B) 39:231 C) 94:181 D) None of these

Explanation:

Copper in 4 kg = $\inline&space;\frac{4}{5}$ kg          and      Zinc in 4 kg = $\inline&space;4\times&space;\frac{4}{5}=\frac{16}{5}$ kg

Copper in 5 kg = $\inline&space;\frac{5}{6}$ kg          and      Zinc in 5 kg = $\inline&space;5\times&space;\frac{5}{6}$ =  $\inline&space;\frac{25}{6}$ kg

Therefore, Copper in mixture = $\inline&space;\frac{4}{5}+\frac{5}{6}=\frac{49}{30}$ kg

and          Zinc in the mixture =$\inline&space;\frac{16}{5}+\frac{25}{6}=\frac{221}{30}$ kg

Therefore the required ratio = 49 : 221

Q:

A milkman claims to sell milk at its cost price, still, he is making a profit of 30% since he has mixed some amount of water in the milk. What is the % of milk in the mixture?

 A) 71.02% B) 76.92% C) 63.22% D) 86.42%

Explanation:

Let the milk he bought is 1000 ml

Let C.P of 1000 ml is Rs. 100

Here let he is mixing K ml of water

He is getting 30% profit

=> Now, the selling price is also Rs. 100 for 1000 ml

=> 100 : K%

= 100 : 30

10 : 3 is ratio of milk to water

=> Percentage of milk = 10 x 100/13 = 1000/13 = 76.92%

7 139
Q:

The milk and water in two vessels A and B are in the ratio 4:3 and 2:3 respectively. In what ratio the liquids in both the vessels be mixed to obtain a new mixture in vessel c consisting half milk and half water?

 A) 8:3 B) 6:7 C) 7:5 D) 11:7

Explanation:

Milk in 1-litre mixture of A = 4/7 litre.

Milk in 1-litre mixture of B = 2/5 litre.

Milk in 1-litre mixture of C = 1/2 litre.

By rule of alligation we have required ratio X:Y

X                  :                 Y

4/7                                2/5

\                      /

(Mean ratio)
(1/2)

/                      \

(1/2 – 2/5)     :       (4/7 – 1/2)

1/10                      1/1 4

So Required ratio = X : Y = 1/10 : 1/14 = 7:5

9 155
Q:

In a mixture of 240 lt. water is 20% and rest is Milk. What quantity of mixture should be taken out and replaced with water so that water becomes 40%?

 A) 60 lit B) 55 lit C) 45 lit D) 50 lit

Explanation:

7 299
Q:

In a 48 ltr mixture, the ratio of milk and water is 5:3. How much water should be added in the mixture so as the ratio will become 3:5 ?

 A) 24 lit B) 16 lit C) 32 lit D) 8 lit

Explanation:

Given mixture = 48 lit

Milk in it = 48 x 5/8 = 30 lit

=> Water in it = 48 - 30 = 18 lit

Let 'L' lit of water is added to make the ratio as 3:5

=> 30/(18+L) = 3/5

=> 150 = 54 + 3L

=> L = 32 lit.

11 615
Q:

A container contains 120 lit of Diesel. From this container, 12 lit of Diesel was taken out and replaced by kerosene. This process was further repeated for two times. How much diesel is now there in the container ?

 A) 88.01 lit B) 87.48 lit C) 87.51 lit D) 87.62 lit

Explanation:

For these type of problems,

Quantity of Diesel remained = $\inline \fn_jvn \left [ q\left ( 1-\frac{p}{q} \right )^{n} \right ]$

Here p = 12 , q = 120

=> $\inline \fn_jvn \left [ 120\left ( 1-\frac{12}{120} \right ) ^{3}\right ]$

=> 120 x 0.9 x 0.9 x 0.9

=> 120 x 0.729

= 87.48 lit.