The concentration of petrol in three different mixtures (petrol and kerosene)

Ques - The concentration of petrol in three different mixtures (petrol and kerosene) is 1/2 , 3/5 and 4/5 respectively. If 2 litres, 3 litres and 1 litre are taken from these three different vessels and mixed. what is the ratio of petrol and kerosene in the new mixture?

(a) 4 : 5

(b) 3 : 2

(c) 3 : 5

(d) 2 : 3

Solution - 

Let,

The three mixture = A, B, C

The concentratoin of petrol in A = 1/2

The concentratoin of petrol in B = 3/5

The concentratoin of petrol in C = 4/5

Now,

2 litres, 3 litres and 1 litre are taken from A, B, C respectively and mixed. (given)

Quantity of petrol taken from A = 2 litres of 1/2

= 2 × (1/2)

= 1

Quantity of petrol taken from B = 3 litres of 3/5

= 3 × (3/5)

= 9/5

= 1.8

Quantity of petrol taken from C = 1 litres of 4/5

= 1 × (4/5)

= 4/5

= 0.8

Therefore,

Total quantity of petrol taken from A, B, C = 1 + 1.8 + 0.8

= 3.6 litres

So,

The quantity of Kerosene = (2 + 3 + 1) - (3.6)

= 6 - 3.6

= 2.4 litres

Thus,

The ratio of petrol and kerosene = 3.6 / 2.4

= 3/2

Therefore,

The ratio of petrol and kerosene = 3 : 2

Hence,

The correct option is (b) 3 : 2.

Thank You