Subject: General Aptitude · Chapter: Alligation or Mixture · Exam: · Marks: · Difficulty:
A can contains a mixture of two liquids A and B in the ratio 7 : 5. When 9 litres of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7 : 9. How many litres of liquid A was contained by the can initially?
(a)10
(b)20
(c)21
(d)25
Answer
Answer (as printed): C
Explanation
Suppose the can initially contains 7x and 5x litres of mixtures A and B respectively. 639 Quantity of A in mixture left 7 21 = 7 x – × 9 litres = 7 x – litres. 12 4 Quantity of B in mixture left 5 15 = 5 x – × 9 litres = 5 x – litres. 12 4 21 7 x – 7 28 x – 21 7 4 ∴ = ⇒ = 15 9 20 x + 21 9 5 x – + 9 4 ⇒ 252 x – 189 = 140 x + 147 ⇒ 112x = 336 ⇒ x = 3. So, the can contained 21 litres of A.
Explanation as extracted from the printed page; notation may be imperfect.