There are two containers A and B filled with mentha oil with different prices

Ques - There are two containers A and B filled with mentha oil with different prices and with volumes 140 and 60 liters respectively. Equal quantities are drawn from both A and B in such a manner that the oil drawn from A is poured in into B and oil drawn from B is poured into A. The Price per liter becomes equal in both A and B. How much is drawn from each of A and B :

(a) 40 litre

(b) 21 litre

(c) 42 litre

(d) Can't be determined

Solution -

Let,

The price per litre of mentha oil in container A = p1

The price per litre of mentha oil in container B = p2

And,

Quantity of oil in container A = 140

Quantity of oil in container B = 60

Let,

x Ltr of oil is drawn from each container and put in the other one.

According to the question 

[(140 - x)p1 + xp2] / 140 = [(60 - x)p2 + p1] / 60

60 [140p1 - xp1 + xp2] = 140 [60p2 - xp2 + xp1]

3 [140p1 - xp1 + xp2] = 7 [60p2 - xp2 + xp1]

420p1 - 3xp1 + 3xp2 = 420p2 - 7xp2 + 7xp1

420p1 - 3xp1 - 7xp1 = 420p2 - 7xp2 - 3xp2

420p1 - 10xp1 = 420p2 - 10xp2

10p1 (42 - x) = 10p2 (42 - x)

p1 (42 - x) = p2 (42 - x)

So,

42 - x = 0   and p1 = p2 

x = 42

x = 42 litre was drawn from each container.

Hence,

The correct answer is option (c) 42 litre.

Thank You